Delhi’s September rainfall has breached the 400-mm mark. (Representational)New Delhi: The monsoon this year has dumped a bounteous 1,160.8 mm of rainfall in Delhi till Thursday evening, the highest since 1964 and the third-highest since the data has been maintained by the India Meteorological Department (IMD).Delhi’s September rainfall has breached the 400-mm mark.At 404.4 mm till Thursday evening, it is the maximum rainfall recorded in the month since 417.3 mm in September 1944.To put things into perspective, Delhi had received 404 mm rainfall in the entire 2019 monsoon period.The figures are still evolving as more rainfall is predicted in the city during the month.Experts say that it is on course to become the second-wettest monsoon ever in Delhi by the time it withdraws.Normally, Delhi records 653.6 mm of rainfall during the monsoon season. Last year, the capital gauged 648.9 mm of precipitation.Between June 1, when the monsoon season starts in the country, and September 15, the city normally gets 614.3 mm of rainfall. The monsoon withdraws from Delhi by September 25.According to the IMD, the Safdarjung Observatory, which is considered the official marker for the city, has received 1,160.8 mm of rainfall this season till Thursday afternoon. It had gauged 1,155.6 mm of rainfall in 1975 and 1,190.9 mm in 1964.The all-time record is 1,420.3 mm rainfall in 1933.Earlier, the weather department issued an orange alert for moderate rain in Delhi during the day. Light rain is likely on Friday.Mahesh Palawat, vice president, Skymet Weather, a private forecasting agency, said, “On and off rains will continue till September 23-24 due to the expected late withdrawal of monsoon.”This means Delhi may record its second-wettest monsoon ever by the time it withdraws,” he said.This is the third time in the last two decades that the monsoon rainfall in Delhi breached the 1,000 mm mark.The city had recorded 1,031.5 mm of rainfall in the monsoon season in 2010. In 2003, the capital had gauged 1,050 mm of it.Delhi received 636 mm, 544 mm, 876 mm, 370.8 mm and 505.5 mm during the monsoon season in 2011, 2012, 2013, 2014 and 2015, respectively.It recorded 524.7 mm of rainfall in 2016, 641.3 mm in 2017, 762.6 mm in 2018, 404.3 mm in 2019, and 576.5 mm in 2020, according to the IMD data.September, in particular, has been bountiful.The city has recorded 404.4 mm of rainfall this month till Thursday evening, which is the highest in 77 years, according to the IMD.The city gauged 417.3 mm of rainfall in September 1944, the highest in the 1901-2021 period.”We still have 14 days left in September. So, it (all-time record) can be broken any moment,” an IMD official said.The September rainfall this year has been in marked contrast to last year, when the city got a meagre 20.9 mm precipitation in the month against a normal of 129.8 mm.Delhi recorded more than 100 mm of rainfall on two consecutive days at the start of the month — 112.1 mm on September 1 and 117.7 mm on September 2. On Saturday (September 11), it recorded 94.7 mm precipitation.Despite the monsoon arriving in Delhi only on July 13, making it the most-delayed in 19 years, the capital recorded 16 rainy days in the month, the maximum in the last four years.The string of rainy days brought 507.1 mm rainfall to the city, which was nearly 141 per cent above the long-period average of 210.6 mm. It was also the maximum rainfall in the month since July 2003, and the second highest ever.The city recorded just 10 rainy days in August, the lowest in seven years, and a cumulative rainfall of 214.5 mm, lower than the average of 247 mm.Delhi has also witnessed seven heavy rain events (64.5 mm to 115.5mm) this monsoon season so far, the highest ever, and these spells account for around 60 per cent of the rainfall recorded in the city. Six heavy rain days were recorded in the 1964 monsoon season.Normally, Delhi records just one or two such events during the entire season, said senior IMD scientist R K Jenamani.The capital recorded three spells of heavy rain in July — 69.6 mm on July 19, 100 mm on July 27, and 72 mm on July 30.While one heavy such episode occurred last month — 138.8 mm of rainfall on August 21, Delhi has already witnessed three such events this month — 112.1mm on September 1, 117.7 mm on September 2, and 94.7 mm September 11 (Saturday).The capital has been logging a new weather record every month since August last year.