Delhi records longest and strongest heat spell in 74 years: Reasons behind the brutal temperatures

El Nino and the monsoon lull are the primary causes of this prolonged heat.

Delhi's primary meteorological station, Safdarjung, has recorded temperatures of 40 degrees Celsius or higher every day since May 13 for 39 consecutive days. According to records, this year was the longest and most intense heatwave in Delhi in 74 years.

As per The Times of India reports, Safdarjung's daily temperature recordings since 1951 show that the longest period of 40+ degrees Celsius before 2024 lasted 32 days, from May 9 to June 10, 1978. This was followed by 27 days starting May 13, 1984, which might be called 34 days if one day with temperatures below 40 degrees Celsius is omitted. Another significant run occurred in 1998, which lasted 27 days and included only one day with temperatures below 40 degrees.

The IMD defines a heatwave day as one in which the highest temperature is 45 degrees Celsius or greater, or when it reaches 40 degrees Celsius and is at least 4.5 degrees Celsius higher than average.

The Times of India also reported that El Nino and the monsoon lull are the primary causes of this prolonged heat. According to these figures, not only has the current heat wave lasted considerably longer than any other in history, but Delhiites have also had to deal with more temperature extremes than at any previous time.

On May 29, day temperatures reached a high of 46.8 degrees Celsius, the second hottest maximum ever recorded at Safdarjung, trailing only the 47.2 degrees C recorded on May 29, 1944.

The only other protracted heat spell in which the highest maximum came close was in 1998 when temperatures reached 46.5°C.

During this time, there have been 12 heatwave days, five in May and seven in June.