Background: The populations of developing nations are more vulnerable to high heat due to poor public health infrastructure and their sensitiveness towards changing climate. Excess mortalities caused by high temperatures have been reported from many parts of the world, including India. In the recent future, more warming and frequent hot days during summer are expected.

Methods: An analysis was carried out to study the effect of maximum temperature (Tmax) on gender-specific all-cause mortality during the summer months (May and June) of 2011 to 2015 in Chandigarh city of India. The mortality is calculated at different thresholds of temperatures of ≤35°C, ≤38°C, <40°C, ≥40°C and ≥42°C. The average number of deaths at temperatures <40°C and ≥40°C were calculated at 99% significance. The Welch t-test is applied to test the significance.

Results: Tmax shows a high degree of association with all-cause mortality in both males and females. Male to female all-cause death ratio was found to be 1.67 for the study period. Daily Tmax of 40°C was found to be the point of inflexion as the number of mortalities at Tmax ≥40°C was significantly higher than those at Tmax below 40°C. The analysis also reveals an increase in the number of death among females at the threshold Tmax ≥40°C indicating higher vulnerability of females at higher temperatures of certain threshold.

Conclusion: A temperature of 40°C should be considered a threshold temperature for issuing heatwave alerts for Chandigarh, India. The increase in vulnerability at temperatures ≥40°C was more among the females