E-Paper
4th coolest May on record across India amid cycle of rain, strong winds
India’s average maximum temperature for the first 30 days of May (data for May 31 will be published only on June 1) was 34.64 degrees Celsius (°C)
New DelhiMay, usually the hottest month, was the fourth coolest across the country since 1951 this year on the basis of average maximum temperature for the first 30 days of the month according to the India Meteorological Department’s (IMD) gridded data. The only exceptions to this were Assam, Kerala, Tripura, Manipur, and Mizoram, which experienced among the seven hottest Mays since 1951. The reason for aberrant May temperatures was rain, which in the case of north and north-western India, was a result of western disturbances, cyclonic systems originating in the Mediterranean. India saw eight of these in May.
India’s average maximum temperature for the first 30 days of May (data for May 31 will be published only on June 1) was 34.64 degrees Celsius (°C). This is the fourth coolest since 1951, the earliest period for which IMD’s gridded data is available, and 1.77°C cooler than the average maximum during the 1981-2010 period. IMD considers the average temperature during the 1981-2010 period as the “normal” against which it measures deviations in temperature.
An analysis of India’s daily average maximum shows that 24 of the 30 days of May were cooler than normal. The warmer than normal days were two three-day-long spells: one from May 11 to May 13 and another from May 20 to May 22. May 21, which experienced the most warming this month, was just 0.61°C warmer than normal.
While most of India experienced a cooler than normal May, the national average expectedly hides regional variations. The record-breaking cooling, for example, was restricted largely to the northern, north-western, and central states. For Jammu and Kashmir, Ladakh, Himachal Pradesh, and Uttarakhand, for example, this was the coolest May by maximum temperature. For another four regions, Delhi, Madhya Pradesh, Chhattisgarh, and Sikkim, this was the third coolest May. In Rajasthan, Punjab, Haryana, Uttar Pradesh, and Telangana, May was the fourth to seventh coolest since 1951.
Since the data for May temperature is available for 73 years, if a state experienced at least the 36th coolest May since 1951, it would be among the cooler half of the 73 May months. This was true for 22 of 30 states and UTs for which this calculation is possible using IMD’s gridded data. Among these 22 states, Bihar was ranked the warmest (only 29th coolest since 1951) and experienced the least cooling (only 0.17°C).
The eight states which experienced a warmer than normal May are Karnataka, Gujarat, West Bengal, Assam, Kerala, Tripura, Manipur, and Mizoram. The latter five of these experienced among the seven hottest May months since 1951. Karnataka, Gujarat, and West Bengal were only ranked 23rd to 24th warmest since 1951.
The cooling in other parts of the country was because of rain. 19 of 33 states and UTs for which this calculation is possible using IMD’s gridded data have received more rain than the 1961-2010 (the average used to check deviation in rain) average this month. However, rain did not have a straight correlation with maximum temperature. For example, India has received 65.8mm rain this month. While this is 11% more than the 1961-2010 average, it is ranked only the 26th highest since 1951, the year since when temperature data is available.
There can be at least two reasons behind maximum temperatures not having a straight correlation with rain. One, if a record amount of rain takes place in a month, but is concentrated in a few days, it may not reduce maximum temperatures for the rest of the month. This did not happen this May and can be seen through the intensity of rain. While overall rain is ranked 26th highest, rain of heavy or extreme intensity was ranked 55th highest since 1951. Light and moderate rain, on the other hand, was ranked sixth and 10th highest.
Another reason for rain not having a straight correlation with maximum temperature can be its timing during the day. If light rain takes place at evening or night, it may not reduce the maximum, which is likely to be recorded during the day. There is no way to measure this timing for all of India, as IMD publishes only the cumulative rain data for the 24-hour period ending at 8.30am on a day.
How long will the cooling continue? Not much longer. The rain and the resultant cooling in May is not likely to carry on in June, the first nominal and official month of the monsoon season, IMD forecasts show. The forecast for June issued by IMD on May 26 shows that most of the country is going to be drier than it usually is in June. This will also lead to higher-than-normal maximum temperatures in the first month of the monsoon season.
The unusual May temperatures again showed that weather patterns were being rendered increasingly unpredictable by the vagaries of the climate crisis. This underlined the need for the authorities to draft policy and plan implementation keeping such anomalies in mind, and for the administration to plan and prepare for it.
