Explaining India’s shift from 13th hottest February to 5th coolest April so far
In 2022, average maximum temperatures were at least a degree higher than normal on all days from March 16 to April 9 except two
With temperatures rising in April, summer finally seems to be arriving in India. Still, this year’s summer, as of now, is still colder than last year’s. To be sure, it has displayed its share of erratic or extreme weather patterns, which are increasingly becoming a norm. Here are four charts based on an HT analysis of India Meteorological Department (IMD) data which explain these patterns in detail.
Maximum temperatures have lagged normal levels since mid-March…
The peak average maximum temperature India has recorded so far is 33.85 degrees Celsius on April 9, according to IMD’s gridded dataset. This is 0.46 degrees lower than the normal – the average of 1981-2010 period – for India on this day. In fact, average maximum temperature has been below normal since March 16; and April 9 was when it came closest to normal. On April 8, for example, the maximum was 33.07°C, 10 days behind schedule according to normal temperatures. This has made the April so far the fifth coolest since 1951, the earliest year for which IMD data is available. In 2022, average maximum temperatures were at least a degree higher than normal on all days from March 16 to April 9 except two, with the nine days of April the ninth hottest since 1951.
... but they were far ahead of normal from February to mid-March
A couple of months ago, it did not look like summer would be running late. IMD officially considers the December-February period as India’s winter. This year, it appeared to be ending before time. The average maximum in the last two weeks of February was slightly above the normal temperature for the first week of March. It wasn’t very cool in early February either. The maximum was higher than normal for 25 out of 28 days in February. On average the month was 1.16°C warmer than normal, making February 2023 the 13th warmest February since 1951. This trend continued in the first two weeks of March, which were each the 22nd warmest this year. Both these weeks were around a degree warmer than normal.
Record-breaking rain…
Most states have experienced cooler than normal maximums since the second half of March because of unusual rain. The rain from March 16 onwards is ranked among the top three since 1901 in seven states, among the top five in 12 states, and among the top 10 in 17. Only Goa and Ladakh have received substantially deficit rain in this period. In contrast, all but eight states were running a deficit in this period last year; and a different set of eight states – mostly in north-western India – had received no rain at all.
…spread over the second half of March has played a role
To be sure, temperatures would not be consistently cool even with record-breaking rain if all the rain fell on a few days. That would allow the temperatures to get back to normal after the rainy days. But rain has also been abnormally consistent this year since the second half of March. For example, in the 1961-2010 period, it rained on average 2.7 and 3.4 days in Gujarat and Delhi from March 16 to April 9. This year, it rained on 17 and 10 days in the two states. In three states –Telangana, Madhya Pradesh, and Rajasthan – it has rained on double or more days than it did on average in the 1961-2010 period. Only in Goa has it rained on fewer days than it did on average during the 1961-2010 period.
Will these trends continue?
Not in the week ending April 20, but IMD has forecast cooler than normal maximum temperatures for all three other weeks up to May 4. To be sure, this does not mean that temperatures will remain just as they are now. A degree’s cooling on May 4 is still going go to be considerably warmer than a degree’s cooling on April 4.
