NEW DELHI: Ominously, three of the six hottest March days recorded since 1951 at Safdarjung have come in the last four years.While the temperature hit 40 degrees C last year, a high of 39.2 degrees was recorded on March 31, 2019.
As per IMD’s criteria for declaring a heatwave, the maximum temperature has to be 40 degrees Celsius or above, it has to be 4.5 degrees or more above normal temperature and these conditions have to persist for two days running.
When the maximum is 6.5 degrees or more above normal —apart from the other conditions — a “severe” heatwave is declared.
“We need two consecutive days for temperatures to remain above 40 degrees Celsius, and the other conditions, for declaring a heatwave,” said R K Jenamani, senior scientist, IMD.
Met officials said the maximum temperature has risen by two-three degrees on each of the last two days following a brief dip in heat due to strong surface winds over the region. At all 13 weather station of Delhi, day temperatures touched 39-41 degrees Celsius on Monday from 34.5 to 35 degrees Celsius on March 26. The temperatures are now above normal by 8 to 9 degrees.
Explaining the factors behind the rise in heat, Jenamani said, “On March 26, the wind speed picked up in the region. Delhi-NCR has been witnessing a prolonged dry spell. The strong winds further dried up the air and cleared pollutants, thus maximising the effect of solar radiation at the surface. Besides, as Delhi-NCR is an urban belt, it heats up more than the neighbouring regions.”.
Also, the winds coming into the capital at present are from north Rajasthan where temperatures are hovering around the 41-42 degrees mark, the official said.
The IMD has issued a ‘yellow’ alert for Tuesday and Wednesday as severe heat wave at many pockets are expected. However, people may get slight relief on March 31 due to a change in wind speed and direction, which may cause a marginal dip in temperature.
