April 2022: Record not just for max but also for minimum, mean temperatures & rainfall

A month of records and contradictions. That was how April 2022 would go down in India Meteorological Department (IMD) records that have been meticulously maintained since 1901.

The unusually dry April has led to the average maximum temperature over the country as a whole being the third highest with 35.30 degrees Celsius after the years 2010 (35.42 degrees Celsius), 2016 (35.32 degrees Celsius) since 1901 while the mean temperature was second highest with 29.41 degrees Celsius after the year 2010 (29.48 degrees Celsius) since 1901.

The average minimum temperature was also the second highest at 23.51 degrees Celsius after the year 2010 (23.54 degrees Celsius) since 1901.

"The absence of active Western Disturbances (WDs) in the month over north India caused highly subdued rainfall and very less thunderstorm activities over northwest and central parts of India. It led to frequent and also prolonged spell of heat wave to severe heat wave days and higher than normal temperature over these areas on most days," IMD explained in its climate summary for the month of April.

The climatological data based on the period of 1981 to 2010 are used to calculate the normal.

Over Northwest India during April, the average maximum temperature was ever highest with 36.32 degrees Celsius in the last 122 years against the earlier record of 35.4 degrees Celsius in 2010. The average mean temperature was ever highest in 2022 with 28.18 degrees Celsius against the earlier record of 27.79 degrees Celsius in 2010. The minimum temperature was second highest with 20.04 degrees Celsius after the year 2010 (20.18 degrees Celsius).

Over Central India during April, the average maximum temperature was highest with 38.04 degrees Celsius in the last 122 years for the period 1901-2022 against the earliest record of 37.75 degrees Celsius in 1973.

Similarly, the average mean temperature was in April 2022 highest with 31.35 degrees Celsius for the period 1901-2022 and it broke the earlier highest record of 31.10 degrees Celsius in 2010. The average minimum temperature was highest in April 2022 with 24.66 degrees Celsius and it broke the earlier record of 24.52 degrees Celsius in 2010.

The monthly average minimum temperature over East & Northeast India for the month of April over East & Northeast India was third highest with 21.94 degrees Celsius since 1901.

West Rajasthan, Himachal Pradesh, south Haryana-Delhi, west Madhya Pradesh, and western parts of Uttar Pradesh experienced higher number of heat wave days and East Uttar Pradesh, east-central India reported lower number of heat wave days.

Meanwhile, in contrast to the month of March 2022, northeast India, and southern Peninsular India, especially Kerala and Tamil Nadu, received scattered to fairly widespread rainfall and thunderstorms on many days in April 2022.

"It is mainly due to the fact that two cyclonic circulations moved from southwest Bay of Bengal to Southeast Arabian Sea across south India during 2nd and 3rd week and north-south troughs/wind discontinuities prevailed from Central India to South Peninsula in the lower tropospheric levels on many days."

Under the influence of cyclonic circulations/troughs in lower tropospheric levels supported by moisture incursion into the area there was fairly widespread to widespread rainfall/thunderstorm activity over Sub Himalayan West Bengal & Sikkim on most of the days and over Northeast India during the 1st half of the month.

April 2022 witnessed extremely heavy rainfall, very heavy rainfall, and heavy rainfall events. Heavy rainfall events occurred mainly over some stations of south peninsular India and northeast India.

Two stations received record rainfall (24 hour) in April. Itanagar in Arunachal Pradesh received 166.6 mm rainfall on April 24 while the previous record of 77.8 mm on April 21, 2016. Similarly, Mawsynram in Meghalaya received 401.8 mm on April 4 against the previous record of 361.8 degrees Celsius on April 28, 1977.

Rainfall over the country as a whole for April 2022 shows that it has recorded 38.4 mm, which is 2 per cent less than its Long Period Average (LPA) of 39.3 mm.

Rainfall over Northwest India (5.6 mm) was third lowest since 1901 after the years 1947 (1.8 mm) and 1954 (4.4 mm). Rainfall over Sub-Himalayan West Bengal & Sikkim (236.8 mm) was third highest since 1901 after the year 1949 (259.9 mm) and 1925 (243.4 mm).

And then, there were contradictions too. During the month, nine sub-divisions of the IMD received large excess, one excess, one normal, five deficient rainfall, 18 large deficient rainfall and 2 sub-divisions did not receive rainfall, IMD data showed.