Number Theory: Rising mercury sets the stage for Holi in the heat | Latest News India

The week to Holi is 5th hottest since 1951

How many people in India do not like being drenched in water on Holi? That is a question only a survey can answer. Existing data, however, shows, whether one likes Holi or not, getting drenched in water this Holi may feel like respite to large parts of India, thanks to the abnormal heat. An analysis of gridded temperature data from the India Meteorological Department (IMD) shows that while March 2022 is not the hottest, second week of March has been among the hottest in most parts of India. This has made the 2022 pre-Holi week one of the hottest pre-Holi weeks in even more parts of India.

First half of March 2022 is only the 25th hottest, but…

According to IMD’s gridded temperature dataset, the average maximum temperature across India in the March 1 to March 15 period this year is 31 degrees Celsius. This is 0.7 degrees, or 2.3%, above normal, which is the average of temperature in 1981-2010. This makes the first half of March 2022 the 25th hottest since 1951.

This is at odds with the reports of heatwaves from large parts of the country. However, maximum temperature for India started going above normal only after March 6 this year. Last week (March 9-March 15), the overall deviation was 1.8 degrees, or 5.9%, making this interval for 2022 the 9th hottest since 1951. March 13, March 14, and March 15 this year are the 9th, 4th, and 3rd hottest since 1951.

Average daily maximum temperature in India.

…the week to Holi is 5th hottest since 1951

The numbers above tell us how hot the week ending March 15 was across years, but not specifically about Holi, since the festival is not celebrated on the same day in the Gregorian calendar every year. Since the latest data available for this year is for March 15, and Holi is to be celebrated on March 18, HT has analyzed the pre-Holi week instead of the festival itself. This has been taken as the period starting nine days before the festival and ending three days before it.

How hot is the pre-Holi week in 2022 in comparison to the pre-Holi week in previous years? It is the 5th hottest since 1951 by maximum temperature. One reason for this high a rank is that in 44 of 72 years from 1951 to 2022, Holi was earlier than March 18, when temperatures are expected to be lower. But that is not the complete story. All hotter pre-Holi weeks than 2022 were in years when Holi was on March 25 or later, which means that this year’s Holi is competing with a slightly hotter period of March. Of the 67 years in which pre-Holi week was cooler, in 23 years Holi was on March 18 or later.

Average maximum temperature in India in five hottest pre-Holi weeks.
Average maximum temperature in India in five hottest pre-Holi weeks.

Pre-Holi week in 2022 among top three hottest in 12 states

The week ending March 15 in 2022 is among the top 10 hottest since 1951 in 15 states, and among the top five in 11 states. Among these 11 are Assam, Kerala, Gujarat, Punjab, Rajasthan, and Himachal Pradesh. The remaining states are those in the North-East, except Meghalaya and Sikkim. Although this week is not ranked close to the top elsewhere, the conditions have been unusual there too. A statistic that highlights how widespread the heat this week has been is that the normal maximum temperature for this week is under 30 degrees Celsius for 15 states, but the 2022 maximum temperature has been under 30 degrees in only five.

Average maximum temperature in week ending March 15 in major states.
Average maximum temperature in week ending March 15 in major states.

As is to be expected, such unprecedented heat has made the pre-Holi week in several states this year one of the hottest ever since 1951. In Gujarat, Himachal Pradesh, Kerala, Punjab, and Rajasthan, this pre-Holi week is among the top three hottest ones. In Haryana and Uttarakhand, it is the fifth hottest. This means in 67 or more years, the pre-Holi week was cooler in these states. In at least 22 of those years, the pre-Holi week was cooler than in 2022 despite Holi being celebrated on or after March 18.

Years of hotter pre-Holi weeks and years of cooler pre-Holi weeks when Holi came on March 18 or later.
Years of hotter pre-Holi weeks and years of cooler pre-Holi weeks when Holi came on March 18 or later.

Delhi’s pre-Holi week not that hot so far, but it might get hotter

Delhi’s pre-Holi week this year is the 8th hottest since 1951. When the full data becomes available and the exact calculations for the week before Holi are possible, it might make the pre-Holi week even hotter. Like in most states, the deviation from normal has increased in Delhi with almost each passing day last week. March 13, March 14, and March 15 in 2022 were the 16th hottest, 10th hottest, and 6th hottest since 1951 in Delhi.

Average daily maximum temperature for Delhi (degrees Celsius).
Average daily maximum temperature for Delhi (degrees Celsius).

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