The Trend of Temperature Changes in Iranian Metropolises in the Last Three Decades

Global warming is a challenging issue among the world's climatologists, embraced even by politicians and the common people. In this study, the trend of temperature changes in 31 metropolises of Iran, which are generally the provincial centres of the country, has been studied in a statistical period of 35 years (1985-2019). We found that there are more temperature changes in all metropolises of Iran in winter than other seasons. In this season, the maximum temperature parameter shows a signicant increase, as evidenced in Ardabil with about 9 degrees Celsius. Also, the highest amount of temperature increase in all seasons has occurred in the western and northwestern part of Iran, being of mildly cold to extremely cold climate in Iran. In general, the temperature changes more intensively from the south to the north regions. It is interesting that in the southern and coastal cities of Iran, such as Ilam, Bushehr and Shiraz, in some months, the temperature keeps decreeing. The increase in temperature of metropolises has been much more regular for the maximum temperature than the minimum temperature. Strangely, unlike all the months in November, the maximum temperature has decreased in most cities in Iran.

temperatures during the period  using parametric methods of linear regression and non-parametric Mann-Kendall showed that the country's temperature is increasing. This increase is more in low and low altitude areas and the trend of increasing the minimum temperature is 60% of the country's area, while the increasing trend of the maximum temperature is 27% of the country. Given that night temperature, as a time of rest, and daily temperature, as a time of activity and work, is important for urban residents. In this study, the trend of minimum and maximum temperature changes in the metropolises of Iran, which is also the largest city in each province, has been studied. The statistical period of this study was selected to include at least 33 years (three solar cycles). Comparison of temperature changes in all metropolises of Iran in a study and a long statistical period has not been done in Iran.
Signi cance of the study The geographical and climatic conditions of Iran have had strong impacts on urban life, especially because of the increase in temperature, and have created issues regarding the fresh water and climate. Therefore, any increase in temperature will greatly affect both of these phenomena. Even in some metropolises, this phenomenon may turn into a climate crisis. However, Iran has a large climatic diversity due to its wide spread along latitude (28˚n to 46˚n). As a result, rising temperatures will have different effects in different climates. In this study, we investigated the changes in temperature in all metropolises of Iran throughout a long statistical period (35 years), which makes this research unique. Considering that metropolises contain more than half of the population of the country, it is essential to study temperature changes in these areas. The results of this research will provide useful information for managers for long-term metropolitan planning. Therefore, this research tries to answer the following questions: 1-Are temperature changes the same in all climates? 2-Which seasons had the highest temperature changes?
3-In which part of the day have temperature changes been the most? (maximum temperature or minimum temperature)? 4-What is the trend of temperature changes from the south to the north of Iran?

Methodology
This research is based on the following steps. In the rst step, daily data of maximum and minimum temperatures of synoptic stations in the period (1985 to 2019) were received from the Meteorological Organization of Iran. In the second step, the statistical basis for the study was determined. To use the most common statistical period of Iranian metropolises, a 35-year statistical period was selected. For this reason, Sari and Yasuj metropolitan stations were removed due to the short statistical period. In the third step, the data of the selected stations were reviewed and their statistical errors were corrected by the methods accepted by the World Meteorological Organization. Figure 1 shows the location of selected metropolises on a map of Iran. In the fourth step, using the daily maximum and minimum temperature data, the average monthly temperature was prepared. In the fth step, using the linear regression equation method, the related calculations were made using MSExcel2019 software and the Insert> scatter command, and after drawing the chart using the Add trend line command and adding options related to R ^ 2 and the line equation. Regression is obtained (dotted lines), through the regression line, and the values of the dependent variable Y can be calculated based on the values of the variable X. In the sixth step, the values of temperature changes for each of the metropolises of Iran were calculated for the two parameters of maximum and minimum temperature as follows. The values A and B were placed in the line equation. Therefore, Time was considered as an independent variable and the monthly temperature of each station was considered as a dependent variable, then the slope of the regression line was obtained.
Temperature changes for stations, in addition to the regression method, were calculated by the method of Mann-Kendall test. In the seventh step, to show the minimum and maximum temperature changes in Iranian metropolises, the calculated statistics in the GIS environment were called. Also, through the Charts index, the bar chart of the maximum and minimum temperature was performed on the Dem map and was then analyzed (Figuer1).
The results obtained from Man Kendall method were almost similar to the linear regression method, and in some cases the regression index provided more accurate results. Therefore, the results of the linear regression method were used in drawing and analyzing the maps.

Results And Discussion
Global warming is one of the most controversial topics among climatologists, politicians and even ordinary people. There are different views regrading climate change and global warming. A group of climatologists completely reject the phenomenon of global warming. Some, however, have fully accepted the phenomenon of global warming. In this study, the trend of temperature changes in Iranian metropolises has been studied over a period of 35 years without any bias from a speci c perspective. Note that in the central and northern part of Iran, four seasons are quite evident. But in its southern part, four seasons are seen only in the national calendar, but in the climatic calendar, no more than two or three seasons are seen. But in this research, the analyzes have been done in four seasons. In April, while the southern part of Iran is almost warm, in the west and northwestern regions, the weather is still cold and plants are beginning to grow and trees are to sprout. As can be seen, the temperature has increased in almost all metropolises of Iran in this month. The highest increase in maximum temperature with 2.2 ° C occurred in the city of Urmia in the northwest and Birjand in the east of Iran. In contrast, the slightest increase of 0.3 °C in the maximum temperature took place in the city of Bushehr on the Persian Gulf coast. The minimum temperature also rose in all cities of Iran (except Gorgan in northern Iran and the cities of Ilam, Shahrekord and Shiraz in the southwest of the country). The highest elevation of 2.5 ˚C in the minimum temperature occurred in the two cities of Yazd and Zahedan, which are located on the edge of the desert. In this month, except in a few cases, in most metropolises of Iran, the temperature rose. In total, in ten metropolises, the sharpest rise in temperature was in the minimum temperature and in 17 metropolises, the highest increase was observed in the maximum temperature ( Figure 3). Figure 4shows temperature changes in Iranian metropolises in May. During this month, the southern cities of Iran enter the warm season. But, in the northernmost cities, it is the most suitable month in terms of human life and ample vegetation. In other words, it is the most suitable month for tourism in most cities of Iran except for the southern regions. In this month, the highest amount of temperature increase of 3.9 °C in the maximum temperature occurred in the city of Mashhad. Conversely, in the city of Bushehr on the south coast of Iran, the maximum temperature has decreased by about 1.3 ˚C. In other cities, the maximum temperature experience an ascending trend. The highest increase in minimum temperature of at least 3.7 °C happened in Ardabil and Mashhad, which are classi ed as cold-region cities of Iran. In the three cities of Ilam (tropical region), Shiraz (in the temperate region) and Shahrekord (the highest city in Iran), the minimum temperature has decreased slightly. In other cities of Iran, the minimum temperature has had a rising trend.

The trend of temperature changes in Iranian metropolises in spring
Figure 5shows the temperature changes in Iran's metropolises in June. This month, the southern cities of Iran experience high temperatures. However, in the western half and the northwest as well as the northeast, the temperature is still favourable and provides good conditions for human life. Also, the highest rise in temperature occurred in the maximum parameter. This increase of 3.4 ˚C occurred in Sanandaj and Ilam in the west of the country. Also in this month, the maximum temperature has decreased by 0.7˚C in the city of Bushehr in the south of Iran, which is located on the north coast of the Persian Gulf. In another metropolitan, the maximum temperatures have been increasing. In 5 cities, the increase has been higher than 3 ˚C and in 12 cities, this amount was more than 2 ˚C. The highest rate of minimum temperature increase occurred in Khorramabad. In contrast, the minimum temperature in Ilam and Shahrekord decreased by about 1.5 ˚C. In the rest of Iran's metropolises, the minimum temperature also increases. In 4 cities, this increase was more than 3 ˚C and in 8 cities it was more than 2 ˚C. Table 1 summarizes the situation of temperature changes in each of the metropolises of Iran in the three months of spring. In April, the maximum temperature increased in 27 metropolises and showed a slight decrease in only two cities. This phenomenon has been repeated in the other two months of spring. But, for the minimum temperature parameter, there was an increasing trend in at least 22 metropolises, with ve other metropolises experiencing a slight decrease. It has been unchanged in the metropolises of Tabriz and Semnan, though. For the two months of May and June, the upward trend occurred in 26 and 27 cities, respectively. Thus, in several metropolises in other metropolises of Iran, both parameters of maximum and minimum temperature have been increasing. In July, as the rst month of summer, the highest increase in maximum temperature, at 3.6 °C, occurred in Gorgan. However, in Bushehr, the maximum temperature decreased by about 0.2 °C. In other cities, the maximum temperature experienced a rise. In 4 cities, this increase was more than 3 ˚C and in 13 cities it was higher than 2 ˚C. The highest increase in the minimum temperature parameter of at least 3.1 °C occurred in Khorramabad. In contrast, in Ilam, Shahrekord and Shiraz, the minimum temperature decreased by at least 2.7, 1.3 and 0.6 °C. But in other cities, the minimum temperature increased. In 8 cities, the minimum temperature this a increased by more than 2 ˚C ( Figure 6).

The trend of temperature changes in Iranian metropolises in the summer season
In August, an increase in the highest maximum temperature occurred in the city of Ardabil (the coldest city in Iran). In this month, the maximum temperature increased by about 4.4 ˚C in the city of Ardabil. In this month, in 5 cities, the maximum temperature increased by more than 3 ˚C and in 5 cities, this increase has been higher than 2 ˚C. In contrast, in Bushehr, the maximum temperature decreased by 0.2 °C. The highest increase in the minimum temperature occurred in the city of Khorramabad at 3.7 °C. In contrast, in Shahrekord, Ilam and Shiraz, the minimum temperature decreased by 2.7, 1.9 and 1.3 °C, respectively. In 8 cities, this increase was more than 2 ˚C. The highest elevation in temperature increase in this month occurred in the northwest and northeastern regions of Iran. On the contrary, in other parts of the country, the rise has been negligible (Figure7).
In September, the highest maximum elevation in temperature of 2.8 °C occurred in Gorgan. But still in Bushehr, although slightly but, the maximum (noon) temperature decreased as much as 0.1 °C, rather slightly. In other cities except for Bushehr, the maximum temperature shows a rising trend. In this month, unlike in previous months, the increase in minimum temperature has been much greater. In this regard, the highest temperature increase of at least 3.7 ˚C occurred in Yazd. In 6 cities, this increase was more than 3 and in 6 cities it was more than 2 ˚C. However, in Ilam, the minimum temperature decreased by at least 2.6 ˚C. Table 2shows the temperature changes of 3 months of summer. The maximum temperature increased in all the three summer months in all cities except in one. This means that the noon temperature is increasing in all metropolises of Iran. Regarding the minimum temperature parameter, in summer, the conditions are slightly different. In July, the temperature dropped in 3 of the 29 metropolitans. The metropolis of Urmia has also remained unchanged. But in other metropolises, the trend has continued to increase. In August, the number of metropolises with a minimum temperature (morning temperature) decreased to 7 cities. But still in 22 metropolises, the minimum temperature is rising. In September, in 4 metropolises, the minimum temperature decreased and in other metropolises, it increased.

The trend of temperature changes in Iranian metropolises in the autumn season
However, with the onset of autumn, temperatures in the northwest and northeastern parts of Iran drop. In the southern half of the country, the weather is still hot where human life and activity are limited. This phenomenon is quite evident, especially in October. The highest increase in maximum temperature has been seen in Zanjan. In 9 cities, the maximum temperature increase was more than 2 ˚C. Meanwhile, in Bushehr, the maximum temperature dropped by 0.3 ° C.
But in other cities, the maximum temperature rose. The increase in minimum temperature was much greater than the maximum temperature. Thus, in the city of Yazd, which is a desert and arid city, the temperature increased by at least 4 ˚C. Also, in 3 cities, the minimum temperature rose by higher than 3 and in 7 cities, the temperature was elevated by more than 2 ˚C. Meanwhile, in the city of Ilam, the minimum temperature has dropped by at least 2.4 ˚C. In the cities of Shiraz, Urmia and Shahrekord, the temperature trend, although small, constantly decreased. In this month, in general, in the arid cities of the deserts of Iran, the temperature increased more than it did in other cities (Figure 9).
In November, metropolitan temperature changes show signi cant differences. The rst noticeable difference is in the amount of temperature change. The highest increase was 2.2 ˚C and the highest decrease was 2.3 °C. Second, in many cities, temperatures fell. In this regard, the maximum temperature in 22 metropolises plummeted. In terms of minimum temperature, in 13 metropolises, there has been a downward trend. Third, in many metropolises, both the minimum and maximum temperatures went down, and in 11 metropolises, both parameters had a falling trend, which is a strange phenomenon in Iranian metropolises ( Figure 10).
There was a slightly different situation for the month of December compared to November This phenomenon is especially evident at maximum temperaturesThus, the maximum temperature continued to rise in 28 metropolises, yet rather slightly. The highest temperature increase with 3.8 ˚C occurred in Ilam station. In terms of the minimum temperature, the situation is almost the same as the previous month. Thus, in 13 metropolises, there was a downward trend in the temperature. The largest decrease occurred in Zahedan at 2.6 ˚C. However, in 16 metropolises, the minimum temperature continued to increase. The highest increase in minimum temperature, with 4.9 ˚C, occurred in Ardabil.
In Table 3, the status of temperature changes in autumn can be observed. In this season, during the rst month, the conditions are the same as the previous months, with a rising trend in the maximum temperature in 28 of the 29 metropolises. In terms of the minimum temperature, the value reaches 25 cities. However, the temperature changes in the next two months are remarkably different especially in November. In this month, the maximum temperature in 22 metropolises was reduced and in three metropolises of Ahvaz, Rasht and Bandar Abbas it remained unchanged. This month, the minimum temperature increased in 16 cities and decreased in 13 others. In December, however, the maximum temperature returned to previous conditions, with 28 cities experiencing an upward trend. Despite that, in terms of the minimum temperature, in 13 metropolises the trend was still falling and in 16 metropolises it was rising.

The trend of temperature changes in Iranian metropolises in winter season
In this season, the northern half of Iran, especially in the rst two months of the season, experience cold weather, yet on the south coast, there is a mild weather then. A preliminary examination of temperature changes shows that two important phenomena have occurred in temperature changes in this season. First, in almost all cities, both the maximum and minimum temperature parameters were incremental. Second, there was a signi cant temperature increase in most cities. Figures 12 to 14 show the temperature changes of Iranian metropolises in winter. In January, the highest temperature increase in the maximum temperature, in Zanjan, reached 5.5 degrees Celsius, which is a high gure. In 13 cities, the maximum temperature increase was more than 3 degrees Celsius and in 10 metropolises, this increase was higher than 2 degrees Celsius, which is considerable. The highest increase in temperature of at least 9.3 °C, which is noteworthy, can be seen in Ardabil. In 6 cities, the increase was larger than 3 degrees Celsius. Meanwhile, in the cities of Ilam, Shiraz and Gorgan, there was a slight reduction in the minimum temperature. Figure 13 shows the temperature changes of February. In this month, the city of Zanjan with 5.2 degrees Celsius had the highest temperature increase in the statistical period of 35 years among the metropolises of Iran. At the same time, in 7 metropolises, the temperature increased by more than 4 ˚C, and in 4 cities, the temperature rose by more than 3 ˚C. during this month, the maximum temperature did not experience any rise in any city. As can be seen on the map, the west and northwest regions had the highest temperature rises. In total, the temperature in this region of the country increased by more than 3 ˚C at the maximum temperature. The lowest temperature rise in this month belonged to the southern and southeastern half of Iran. The highest elevation in the minimum temperature (morning temperature), still with 5.2 °C, belongs to the city of Zanjan. The cities of Ardabil, Arak and Yazd are next with 4.8, 4.2 and 4.2 C, respectively. In 3 cities, an increase of greater than 3 ˚C is seen. In terms of minimum temperature parameter, the highest rise in temperature occurred in the northwestern and western parts of Iran. The southern and southeastern parts still show the least increase.
It can be observed in the March map that the highest cumulative temperature rise occurred this month. As can be seen, the highest maximum temperature increase of 6.8 °C still occurred at Zanjan station. It should be noted that in Urmia and Arak stations, the temperature increased by 6.4 and 6.3 ˚C. In 11 stations, the temperature of higher than 5 ˚C and in 9 stations, an increase of larger than 4 ˚C occurred. As can be seen, the temperature rose signi cantly in all cities except the southern coastal cities. The increase in the minimum temperature was the same as the maximum temperature this month when in 13 cities, the temperature increased by more than 3 ˚C. This signi cant increase in temperature mainly occurred in the west and northwest region and then on the shores of the Caspian Sea. This region is one of the rainiest and at the same time the most pleasant and airy regions of Iran. Table 4 demonstrates the trend of temperature changes in Iranian metropolises during the winter months. As can be seen, in every three months of winter, the maximum temperature increased in all metropolises of Iran. The minimum temperature slightly decreased in only three metropolises in January. But in other cities, the trend was still rising. In the other two months of the winter, the minimum temperature increased in all cities.

Discussion
Global warming is a challenging issue for countries that are located in the hot and dry regions of the world and are struggling with the problem of water shortage and drought. In countries facing the problem of water shortage, drinking water supply for the urban population, especially for Metropolises, is a major problem. Most of these metropolises in hot and dry areas lack large rivers or rich groundwater resources. As a result, the increase in temperature, in addition to affecting the comfort, living and activities of human beings, but also with increasing urban water consumption (drinking, cleaning, etc.) makes the water supply of cities with serious problems. Water shortages in hot seasons may become a crisis too.
Iran has 31 metropolises, most of which are located in provincial capitals. Except for the metropolis of Ahvaz, through which a river ows, other metropolises of Iran do not have strategic rivers. The vast majority of these cities are located in large plains or foothills.
In this study, the trend of maximum and minimum temperature changes in all metropolises of Iran except Sari and Yasuj was studied in a statistical period of 35 years (1985-2019) (These two cities did not have a su cient statistical period). The ndings of the present study are as follows: 1. In the three months of spring, the three metropolises of Ilam, Shahrekord and Shiraz (which are generally located in the southern part of Iran) as well as Gorgan, which is a coastal city in the north of the country, experienced a slight decrease in temperature. In other metropolises, there was an increasing trend every three months of spring. This increase in temperature between one and a maximum of 3.9 ˚C was observed in the city of Mashhad (in the northeast of the country). Early in the season, most changes occurred in the cities of the eastern half of Iran. However, in the following months, the highest temperature increase occurred in the cities of the northern and northwestern parts. Figures 15 and 16 show the trend of temperature changes for Iranian metropolises in the 35-year period in spring. In this chart, cities are adjusted based on latitude and from low to high. As can be seen on the graphs of temperature changes, the increasing trend of temperature has intensi ed from the south to the north of the country. Basically, the increasing trend in the maximum temperature parameter was more homogeneous than the minimum temperature. In the two metropolises of Ilam and Shahrekord, the minimum temperature has decreased abnormally and in the metropolis of Ardabil there has been an unusual increase.
2. In summer, except for the city of Bushehr in the south, in all metropolises of Iran, the maximum temperature shows an increase. The increase in temperature in a city like Ardabil, which is one of the coldest cities in Iran, reached 4.4 ˚C. As for the minimum temperature parameter, at least in 4 metropolises, the temperature trend was falling, but in many cities, the trend was rising. The highest increase in minimum temperature reached at least 3.7˚C. Figures 16 and 17 show the trend of temperature changes in the summer months. As can be seen in the diagram, there was a sharper trend of increase, especially for the maximum temperature parameter from south to north of the country. In this season, the highest values of increase in both maximum and minimum temperature parameters occurred in the northwestern region of Iran.
3. In the rst month of autumn, the temperature is almost the same as in previous seasons. In this connection, except in one city in the maximum temperature parameter and 4 cities in the minimum temperature parameter, in other cities the temperature constantly rose. Therefore, the minimum temperature in the city of Yazd increases to 4 ˚C. An important phenomenon that distinguishes this season from other seasons is that the temperature changes in the other two months of autumn, especially in November, show a signi cant difference with other months of the year. In many metropolises, the temperature decreased in both maximum and minimum temperature parameters. In November, the maximum temperature in 22 metropolises and the minimum temperature in 13 metropolises decreased. This is an unusual phenomenon in this month of autumn. Figures 18 and 19 demonstrate the trend of temperature changes in autumn. 4. In winter, the phenomenon of heating is serious in the metropolises of Iran. As seen on the chart, the maximum temperature rose constantly in all metropolises without exception. This phenomenon was repeated in the minimum temperature parameter except for the three cities of January. Another notable phenomenon is the amount of temperature rise. In this regard, the temperature rises to about 9.3 ˚C in a cold city like Ardabil. In other cities, increases of 4 to 6 ˚C are seen in the maximum and minimum temperatures. Figures 20 and 21 show the trend of temperature changes in winter.

Conclusion
Based on the ndings, the rising trend of temperatures in Iranian metropolises is a serious issue. To answer the rst research question, it was observed that temperature changes were not the same in all climates. An important issue is that the greatest increase in temperature occurred in the cities of the western and northwestern part of the country. As mentioned earlier, these cities have a cool climate. Most of the winter rainfall in this part of Iran is in the form of snow.
Due to the climatic conditions of Iran, snow is suitable water storage for feeding groundwater aquifers. A signi cant increase in temperature in this part of Iran will be a matter of concern in terms of water balance because it will gradually change the type of precipitation from solid to liquid. On the other hand, snow storage at high altitudes will melt earlier than usual and will be out of reach in seasons when water is not much needed. As a result, these cities will face a serious water shortage problem in the future. In contrast, the increase in temperature in the southern regions of the country, which have a tropical climate, was very slight and sometimes decreased moderately.
The answer the second research question, temperature changes have not been the same in all seasons. The greatest increase in temperature occurred in winter. This is not a good sign for a country with an arid and semi-arid climate. Conversely, in the last two months of the fall season, especially in November, the trend of temperature changes fell in many cities. This is an unusual phenomenon, which should be investigated in a separate study.
In answer to the third question, this study showed that the values of temperature increase at maximum temperatures (noon temperature) were higher than minimum temperatures. The increase in the maximum temperature was a more stable trend in all metropolises. Therefore, the increase in temperature in Iranian metropolises became a trend. Due to the problem of water shortage in Iran and the adaptation of the cultivation period of many crops to the warm period of the year, the phenomenon of rising temperatures will greatly increase the amount of water used in agriculture and drinking.
In answering the fourth question, this study showed that the values of temperature increase from the south to the north of Iran were intensi ed. This increase in temperature will increase the amount of water consumed in the metropolises of the temperate and cold regions. Cities that, in the current situation, face less problems in terms of urban drinking water supply, face the problem of water shortage in the future.The results of this study are consistent with the research Dear Prof. Dr. Hartmut Graßl I would like to submit the manuscript entitled "The trend of temperature changes in Iranian metropolises in the last three decades" by Hassan Lashkari Nahid ghorlivand, Zainab Mohammadi,Hossein Ali Rouhbakhsh Sigaroodi to be considered for publication as an original article in the Theoretical and Applied Climatology We declare that this manuscript is original, has not been published before and is not currently being considered for publication elsewhere. This manuscript is part of the results of the MSc. dissertation of the corresponding author, which has been defended at the University of Shahid Beheshti(SBU)under the supervision of the rst author.
Funding: there has been no signi cant nancial support for this work that could have in uenced its outcome. Con icts of interest/Competing interests: We know of no con icts of interest associated with this publication and we have no potential con ict of interest in relation to the study in this paper.
Availability of data and material: All data and material used in this article is available and could be provided.
Code availability: 'Not applicable' As Corresponding Author, I con rm that the manuscript has been read and approved for submission by all the named authors.
We hope you nd our manuscript suitable for publication and look forward to hearing from you in due course. Geographical location of the selected metropolises in this study. Long-term temperature changes  in Iranian metropolises -April.

Figure 5
Long-term temperature changes  in Iranian metropolises -June.

Figure 7
Long-term temperature changes  in Iranian metropolises -August.

Figure 10
Long-term temperature changes  in Iranian metropolises -November.

Figure 12
Long-term temperature changes (1985-2020) in Iranian metropolises -January Figure 13 Long-term temperature changes (1985-2020) in Iranian metropolises -February Figure 14 Long-term temperature changes (1985-2020) in Iranian metropolises -March Figure 15 The trend of long-term changes in the maximum temperature average in the metropolises of Iran -(Statistical period 1985-2019) -spring season.

Figure 16
The trend of long-term changes in the minimum temperature average in the metropolises of Iran -(Statistical period 1985-2019) -Spring season.

Figure 17
The trend of long-term changes in the maximum temperature average in the metropolises of Iran -(Statistical period 1985-2019) -Summer season.

Figure 18
The trend of long-term changes in the minimum temperature average in the metropolises of Iran -(Statistical period 1985-2019) -Summer season.

Figure 19
The trend of long-term changes in the maximum temperature average in the metropolises of Iran -(Statistical period 1985-2019) -autumn season.

Figure 20
The trend of long-term changes in the minimum temperature average in the metropolises of Iran -(Statistical period 1985-2019) -autumn season.

Figure 21
The trend of long-term changes in the maximum temperature average in the metropolises of Iran -(Statistical period 1985-2019) -Winter season. Figure 22