Mercury plummets 11.9°C in a day, caps off a hotter than normal June in Delhi

While Delhi received 116.6mm rain on June 30, it took place after 8.30 am on Thursday. This means that it will be accounted for in July’s rain data. The IMD calculates the day’s rainfall reading between 8.30am and 8.30am the next day.

The average wet-bulb temperature, another measure of how humidity impacts thermal discomfort and how easy or difficult it is to work outside, was recorded at 27.19 degrees. A wet-bulb temperature of more than 29 degrees makes it uncomfortable to work outside in the open. When it goes over 32 degrees, it is difficult for even fit and acclimatised people to work outside.

A view of Delhi-Meerut Expressway during heavy rain in New Delhi, India, on Thursday, June 30, 2022. (Photo by Ajay Aggarwal/Hindustan Times)

While Delhi received 116.6mm rain on June 30, it took place after 8.30 am on Thursday. This means that it will be accounted for in July’s rain data. The IMD calculates the day’s rainfall reading between 8.30am and 8.30am the next day. As a result, for June 30, Delhi only received ‘trace’ rainfall before 8.30am on Wednesday and 8.30am on Thursday. Meanwhile rainfall from 8:30 am on Thursday until 8.30am on Friday will be taken as rainfall received in Delhi on July 1.

Similarly, for record-keeping purposes, Thursday’s maximum temperature, which is recorded at 5.30pm, is therefore accounted for in July data, with IMD’s record books ending the month with a maximum temperature of 40.9 degrees Celsius on Wednesday. This means Delhi’s average monthly maximum temperature, according to the IMD chart, was 40.4 degrees.

On an average, July receives 210.6mm rainfall. Already, Delhi has recorded 116.6mm of rainfall for July. Last year, July recorded 507.1mm of rainfall in total – over two-and-a-half times the monthly normal. (HT Illustration)

“Delhi has only seen one active western disturbance throughout the month and there was no rainfall in the first two weeks, where temperatures consistently remained above 40 degrees,” said IMD scientist, RK Jenamani.

“Delhi then saw its only western disturbance between June 16 and 20, when temperatures dropped down to around 30.7 degrees too. However, we have now seen a return of rainfall only on the last day of the month,” Jenamani said, and added that this largely occurred after 8:30am and will not official be part of June’s rainfall data.

Delhi has seen poor rainfall over the last four months. Delhi received zero monthly rainfall in March, as against a normal of 15.9mm, 0.3mm in April compared to normal of 12.2mm; 47.7mm rain compared to a monthly normal of 19.7mm in May, and recording a deficit again for June, which saw only six rainy days and primarily very light to light showers, shows IMD data.

On an average, July receives 210.6mm rainfall. Already, Delhi has recorded 116.6mm of rainfall for July. Last year, July recorded 507.1mm of rainfall in total – over two-and-a-half times the monthly normal.