Weather Bee | How bad is the heat in India this May?

The answer depends on an analysis of average maximum weekly temperatures, with heat moving from the southern parts of the country to the northern parts

How bad is the heat in India this May? Depending on where a person lives in the country and what part of the month they are talking about, the answer to this question might differ drastically. For example, a person living in Kerala might say that the month started off very hot, but is mild now. On the other hand, a person living in Delhi is likely to have found the month mild in the beginning but is likely to feel very hot right now. Here is how.

New Delhi, India - May 20, 2024: Visitors brave the Heat Wave in hot summer at Kartvaya Pathlawns , in New Delhi, India, on Monday, May 20, 2024. (Photo by Vipin Kumar/ Hindustan Times) (Hindustan Times)

If the average maximum temperature for the month so far is analysed, very few states appear to have experienced a hot May. According to India Meteorological Department’s (IMD) gridded data, the average maximum temperature in the first three weeks of May (the data for May 22 will only become available on May 23) is ranked in the top ten this year (since 1951) in only six out of thirty states for which this calculation is possible. Only these six states – Mizoram, Manipur, Assam, Gujarat, Kerala, and Rajasthan – are experiencing a maximum temperature warmer by more than 1 degree Celsius compared to normal.

However, reading just the average for the month might be misleading. While this average tells the overall picture of the month, it does not tell how hot different parts of the month were. To analyse the trends in different parts of the month, HT calculated the average maximum in each of the three weeks of May to date. This shows that while only six states have experienced one of the top ten hottest temperatures in May since 1951 overall, the number of such states was higher in weekly averages of maximum temperatures. Seven states experienced one of the top ten hottest first weeks of May this year. This number decreased to four in the second week of May but was eleven in the third week.

To be sure, ranks alone can also be misleading in a world affected by climate crisis as temperature records are broken almost every year. Out of 30 states, 10 experienced an increase in temperatures of more than 1 degree Celsius in the first week of May, whereas eight states experienced an increase in temperatures in the second week and 15 in the third week.

Why does the number of such states decrease when looking at the average for the month overall so far? This is because heat has travelled over different parts of the country during the month. For example, the states warmer by more than 1 degree Celsius in the first week of May were either peninsular states or eastern states. They were Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Telangana, Odisha, Jharkhand, Bihar, West Bengal, and Mizoram. Out of these ten states, only Bihar, West Bengal, and Mizoram kept this trend in the third week. They were joined by other northern states – such as Punjab, Haryana, Delhi, Rajasthan, and Uttar Pradesh – in the third week.

These weekly trends mostly reflect the fact that the heat has moved from the southern parts of the country to the northern parts as the month has progressed. This is because the northern half was keeping cool due to rain and clouds from western disturbances in the earlier parts of May. With western disturbances weaker, they have warmed up in the latter parts of the month. On the other hand, the southern states, which were parched in the early parts of the month, are now rainy and cool as low-pressure areas in the seas around them are causing rain.

Abhishek Jha, HT’s senior data journalist, analyses one big weather trend in the context of the ongoing climate crisis every week, using weather data from ground and satellite observations spanning decades.