This July was 6th warmest since 1901, says IMD
July 2021 was the sixth warmest July on record in India since 1901 with a mean temperature of 28.52 degrees Celsius — 0.55 degrees above normal — according to the climatological data maintained by India Meteorological Department, Pune.
It was the third warmest July when minimum temperatures are considered and eighth warmest in terms of maximum temperatures.
The mean temperature is calculated as the average of maximum and minimum temperatures for the month.
This July was marked by extremely warm nights almost all over the country except peninsular India which recorded above-normal rains in July. Climatological data between 1901 and now also indicates that four of the five warmest Julys on record have been in the past decade, indicating a rising trend in temperatures in recent years.
There was a 7% rain deficiency in July over the country with a 26% deficiency over east and northeast India, 7% deficiency over northwest and central India, but 27% excess rain over peninsular India. The monsoon covered most of the country by June 19 except parts of Rajasthan, Delhi, Haryana and Punjab. After that, the monsoon entered a “break” phase till July 11. OP Sreejith, head, climate monitoring and prediction group, IMD Pune, said high minimum and maximum temperatures in July are linked to deficient rain and a long dry spell.
The warmest July recorded was in 2019, logging a mean temperature of 28.65 degrees Celsius, 0.68 degrees above normal; the second warmest July was in 2015 recording a mean of 28.63 degrees Celsius; the third was in 1987 with a mean of 28.61 degrees C; the fourth in 2014; and the fifth in 2020.
In terms of minimum temperature, it was the third warmest with a minimum temperature of 24.88 degrees C, 0.56 degrees above normal. The highest was recorded in 2019 at 24.91 degrees C; the second highest in 1903 at 24.89 degrees C; and the fourth and fifth highest minimum temperatures were recorded in 2014 and 2015, respectively.
The average maximum temperature this July was 32.16 degrees Celsius, 0.54 degrees above normal and the eighth warmest on record. The highest July average maximum was recorded in 1987 at 32.53 degrees C, 0.91 degrees above normal. The next highest was in 2015 at 32.45 degrees C.
“Temperatures were high because clouding was less in the first half of July. Rain picked up in southern parts of the country in July. Many factors may have contributed to a warm July, including the climate crisis. In recent years, temperatures are high and creating records,” said a senior meteorologist from IMD who did not wish to be named.
El Nino years are normally linked to very warm summers in India. This year, however, El Nino and Southern Oscillation (ENSO)-neutral conditions prevailed. Had it been an El Nino year, along with such break monsoon features, it could have been much warmer, scientists said.
ENSO is a periodic fluctuation in the sea surface temperature and the air pressure of the overlying atmosphere across the equatorial Pacific Ocean, according to the National Oceanic and Atmospheric Administration.
ENSO has a major influence on weather and climate patterns such as heavy rain, floods, and drought. El Niño has a warming influence on global temperatures, whilst La Niña has the opposite effect. In India, for example, El Nino is associated with drought or weak monsoon while La Nina is associated with strong monsoon and above-average rains and colder winters.
“There were heatwave conditions over many parts of northwest India early in July. The minimum temperature was high from the beginning. Heatwave conditions were reported from Rajasthan, Haryana and Delhi NCR. Rainfall was less due to break monsoon, so temperatures soared,” explained Mahesh Palawat, vice president, climate change and meteorology, Skymet Weather, a private weather forecasting company.
Average minimum temperatures in July were the second highest on record over northwest India at 24.42 degrees Celsius, 0.87 degrees above normal while over central India they were the highest at 25.18 degrees Celsius, 0.46 degrees above normal.