One of the researcher of this study who is also a medical doctor with experience of 18 years have suspected that there are season and temperature variations in India on the number of adolescent/adult mortality due to Heart disease / Hypertension. During regular duties at various Government hospitals, the researcher felt some trends in the title-mentioned research question. Hence the researcher decided to investigate the query mentioned in the title with proper evidence and accredited data. The key purpose is to alert the policy-makers, caregivers, medical doctors, patients, decision-makers, researchers, and citizens of India, etc through evidence-based study to take proper care during the seasonal and temperature variations which may harm persons with Heart disease / Hypertension. There are several research studies done on the impact of season and temperature on hypertension and related mortality which established that a relationship exists between them. Despite being the second-most populous country of the world with wide variations of seasons/temperature, the researcher has not found any adequate broad country-based study conducted in India for evaluating the impact of temperature / seasonal variation on the number of adolescent/adult mortality due to Heart disease / Hypertension in the general population. CVDs (Heart Diseases) are the most important cause of death accounting for 17.9 million people's mortality globally in 2019, representing 32% of all global mortalities; of which 85% were caused by heart attack and stroke. Hypertension is a serious medical condition of elevated blood pressure that increases the risks of heart diseases; 1.28 billion adults globally have HTN and two-thirds (66%) of these are living in low- and middle-income countries (LMICs) like India. This is a novel cross-sectional research study with the key objective to analyze the impact of season and temperature variations on the mortality trends of adolescents/adults due to Heart disease / Hypertension with the utilization of time-bound accredited data. The title mentioned research question is not well understood to date and this research study tries to find an answer through one factor only i.e. mortality data. This research study was a Country / HMIS (MoHFW) accredited data-based retrospective cross-sectional study conducted across all HMIS registered public/private/rural and urban health facilities of 36 states and UTs (union territories). The study population for this novel research study consisted of any adolescent (10 to 19) / adult (19 and above) of both sexes. The three years of study when combined shows that the Heart disease / Hypertension mortalities were highest in January with 89417 mortalities ([95% CONF. INTERVAL] 84795.48–94038.52 ; STD. ERR.-1074.109; MEAN-29805.67; STD. DEV.-620.1374; MIN-29346; MAX-30511 followed by September-85633 (95% CONF. INTERVAL- 57391.89–113874.1)and December-83682 (95% CONF. INTERVAL − 73045.63–94318.37) while lowest mortalities were found in April – 66116 (95% CONF. INTERVAL- 49641.4–82590.6 ). The mean seasonal mortality for Heart disease / Hypertension mortalities was highest in the Winter Season Jan-Feb (mean temperature 20.91 C) having mean mortality of 28322.33 followed by post-monsoon (mean temperature 23.59 C) with mean mortality of 27458.33, monsoon (mean temperature 28.44 C) with mean mortality 26197.83 and pre-monsoon (mean temperature 27.91 C) having lowest mean mortality 23302.22.