Barmer in Rajasthan may have been the hottest place in India on Thursday at 43.4°C, but the maximum temperature surges were recorded in hill-station favourites Kullu in Himachal Pradesh and Mukteshwar in Uttarakhand.
According to figures on the India Meteorological Department (IMD) website, these towns recorded 32°C and 27.2°C — a searing eight degrees above normal for the last week of March.
Other summer getaways in north India, such as Shimla also in Himachal Pradesh, Pahalgam in Jammu & Kashmir and Dehradun in Uttarakhand have all registered temperatures seven degrees above their historical normals.
What is a heat wave?
While there are caveats, the IMD’s dictionary says that if a locations’ long-term normal is less than or equal to 40°C, a five-degree rise in temperature counts as a heat wave and seven or more, as a severe heat wave.
The IMD had already warned of summer temperatures being higher than normal in February and “above normal” temperatures in Himachal Pradesh, Uttarakhand, Jammu and Kashmir. 2016 was the warmest year in a century, according to the IMD, with the country 0.91°C warmer than the 1961-1990 average.
The summer months of March-May last year were 1.36°C higher than historical average, making it the second-warmest since 1901.
(Temperatures measured in °C)
The high temperatures in the north, according to a senior IMD official, are due to a confluence of weather conditions such dry south-westerly winds from Gujarat blowing to the north and approaching Western Disturbances (a storm from the Mediterranean that brings rain to north and northwest India). These are coupled with an anticyclone, a clockwise spiraling of air that pulls in more warm air flowing in from the south-west.
“By April 1, the heatwaves will start to subside (due to the rain),” said M Mohapatra, head-meteorologist at the IMD’s National Weather Forecasting Centre. “But these places have seen higher temperatures in earlier years too.”
Historical data, until 2010, on the IMD website says that Shimla’s highest-ever maximum temperature in March was 25.8°C in 2010 and Mukteshwar, 28.5°C in 2004.
The stamp of global warming is evident in this year’s searing March. “When the average temperatures are rising every year, there will be more incidents of extreme temperature,” Mr. Mohapatra added. North India apart, several states — Madhya Pradesh, Maharashtra, Chattisgarh, Orissa, Jharkhand and Rajasthan — recorded severe-heat wave conditions because of the meteorological confluence.
As The Hindu reported earlier this week, the IMD is already in the process of informing States to put in place comprehensive heat action plans to prepare for the summer.
