Not only was February 2023 the hottest February since the year 1877, but India’s minimum temperatures – used to indicate how cold a night is – were also the fifth highest in this month’s history of recorded temperatures. In simple words, nights were not as cold as they used to be.
A breakdown by region for February 2023 shows northwest, east and northeast India’s minimum temperatures were their second-highest ever. Even in March 2023, the country’s average minimum temperature was 0.59 degrees Celsius above normal.
In our #TIL explainer, we explain rising minimum temperatures, warm nights and why they matter.
Tracking warm nights
When days are hot, nights give the human body a chance to cool down. But when nights get warmer, that does not happen, leading to increased heat stress on the body. The combined effect of a warm day and warm night is detrimental to human health. The relative mortality risk on days with hot nights could be 50% higher than on days with non-hot nights, a 2022 paper that analyzed mortality across 28 cities in Japan, South Korea and China had noted.
Health risks due to daytime heatwave can substantially increase if the human body does not get a break from the heat during night, a 2017 paper by researchers from China.