Over a month of monsoon to go, rain already past season’s normal in Delhi

This means that any rainfall recorded between now and the end of September will only help take the city further into the “excess” category

In what has clearly been a rain-heavy monsoon, Delhi has already received more rainfall so far than it normally does throughout the monsoon, despite one-and-a-half months of the season still yet to come, official data shows.

This is the fastest year that Delhi has crossed the long-period average (LPA) of 640.4mm – what is considered the “normal” mark for monsoon rain. (Raj K Raj/HT Photo)

This means that any rainfall recorded between now and the end of September will only help take the city further into the “excess” category.

In fact, this is the fastest year that Delhi has crossed the long-period average (LPA) of 640.4mm – what is considered the “normal” mark for monsoon rain – since at least 2014, the latest this data is maintained by the India Meteorological Department (IMD).

With 13mm of rainfall logged in the city between 8.30am and 5.30pm on Monday, Safdarjung – representative of Delhi’s weather – crossed the LPA threshold, with total rainfall since June 1 at 648.3mm.

The last time Delhi managed to cross its average annual monsoon mark in August was 2021, when it did so on August 21, data showed.

Monday’s spell also helped Delhi cross 200mm of monthly rainfall in August, making it now the third month in a row that this has happened. The month’s rainfall at Safdarjung stood at 201.2mm till 5.30pm on Monday, according to IMD data. The average for August is 233.1mm.

Delhi recorded 243.3mm in June – an excess of 228% over the normal monthly average of 74.1mm. In July, the city received 203.7mm precipitation, just short of the monthly average mark of 209.7mm.

IMD classifies the months of June, July, August and September as monsoon months, with the average monthly rainfall total used to give the year’s monsoon rainfall.

The LPA for September is 123.4mm.

Last year, Delhi recorded 660.8mm rain throughout the four monsoon months. The cumulative total for monsoon was 516.9mm in 2022; 1,169.7mm in 2021 and 576.6mm was recorded in 2020. The lowest monsoon total in the last decade was 370.8mm, which was recorded in 2014.

In fact, Delhi has managed to cross its annual monsoon average mark on only on four occasions since 2014, IMD data shows.

It did so on September 17 in 2023; on August 21 in 2021; September 4 in 2018 and on September 23 in 2017. In the remaining years, Delhi received a sub-par monsoon at Safdarjung.

The normal date for departure of the southwest monsoon from Delhi is September 25.

RK Jenamani, scientist at IMD said that from the second week of August, the monsoon trough has remained close to Delhi-NCR, giving the capital steady light to moderate rain. Delhi has also managed to record rain on 11 out of the 12 days so far this August.

“The longer the trough says close to a region, the more rain is recorded. In the last few days, we have seen steady activity due to rain,” he said.

Experts said June and July were in stark contrast to what was observed in August – the monsoon trough mainly stayed away from the region.

“It was only on June 28, when the monsoon arrived in Delhi that over 200mm was recorded in a single day. The trough stayed away from Delhi-NCR most of July too, and only on July 31 did the trough return over Delhi-NCR, with most stations logging over 100mm in rainfall,” said Mahesh Palawat, vice president at Skymet meteorology, a private weather forecasting service.

Since June 28, at least 33 rain-related deaths have been reported across Delhi, with widespread chaos, building collapses, flight diversions and inundation reported on multiple days. The deaths that have occurred include electrocution deaths and drowning incidences too. Among these deaths were three IAS aspirants, who drowned due to intense showers in a coaching centre basement in Old Rajendra Nagar on July 27.

The spell of rain, however, is likely to continue, if one were to believe IMD’s forecasts.

IMD has forecast scattered rain to continue in Delhi till the weekend, with light rain likely on Tuesday and light to moderate showers on Wednesday.

Delhi’s maximum temperature meanwhile stood at 31.6°C on Monday, which was three degrees below normal. It was 31°C a day earlier. The minimum temperature was 24.8°C on Monday. It was 26°C a day earlier.

Meanwhile, the rain also helped Delhi’s air remain “satisfactory” for a 16th straight day. The 24-hour average air quality index (AQI) stood at 56 (satisfactory) at 4 pm on Monday. It was 69 (satisfactory) at the same time on Sunday.