Rainfall pattern in Bengaluru increasingly showing variation, IMD data indicates

Not only has the annual rain in Bengaluru increased, but there is a variation in the monthly rainfall pattern as well. While the average rain for May is 107.4 mm, this year the IMD recorded 253.9 mm. June this year was the wettest in ten years with 206 mm of rainfall.

According to the India Meteorological Department (IMD), the city has received a total of 1,795.5 mm rainfall this year, breaking the annual record of 1,696 mm in 2017. (Express file photo by Jithendra M)

Since October 1, Bengaluru has received 311 mm of rainfall, a departure of 189 mm from the normal. The previous record of the city having received the highest rainfall during the month in recent years was in 2017 when Bengaluru recorded 385.7 mm. According to the India Meteorological Department (IMD), the city has received a total of 1,795.5 mm rainfall this year, breaking the annual record of 1,696 mm in 2017.

After a decrease in October rainfall in 2018 (111.7 mm), it has only grown over the years. The rainfall recorded in October 2019 was 178.4 mm, while it was 204.3 mm in 2020 and 366.3 mm in October 2021, which was the second wettest month since 2017.

However, the all-time record for October rainfall was reported in 2005 when Bengaluru received 605.6 mm of rain.

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According to the IMD, every year during October and November, the city receives heavy rainfall. “Our records show that in October 2005, Bengaluru received 605.6 mm of rainfall. The heaviest rainfall in 24 hours in October was 178.9 mm on October 1, 1997. October and November are the months which receive heavy rainfall. Owing to increasing concretisation, the rainfall pattern has also been erratic and the city is receiving heavy rainfall,” an IMD scientist said.

Variation in monthly rainfall pattern

Not only has the annual rain in Bengaluru increased, but there is a variation in the monthly rainfall pattern as well. While the average rainfall for the month of May is 107.4 mm, this year the IMD observatory recorded 253.9 mm.

According to the Met department, June this year was the wettest in ten years with 206 mm of rainfall. In June 2015, the city recorded 191.3 mm of rainfall, while Bengaluru received 177.1 mm of rain in June 2012.

Against an average of 116.4 mm of rain in July, the city received 197.8 mm of rainfall this year. While last year Bengaluru received 98.5 mm of rain in August, this year it received 364.2 mm, just short of the all-time record (set in 1998) of 387.1 mm for the month.

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In the June-September season this year, the city has received more than 1,032 mm of rainfall against an average of 661 mm. The previous record for this period was 949.7 mm in 2017.

The IMD data also shows that the average rainfall in Bengaluru has increased by 9 per cent. The average rainfall has increased from 986.8 during the 1981-2010 period to 1,077.8 mm during 1991-2021.

According to the Met department, the previous wettest year on record was 2005 when the city received 1,608.5 mm of rainfall. The annual rainfall in Bengaluru recorded in 2021, 2020, 2019 and 2018 was 1,500 mm, 1,200 mm, 950 mm and 1050 mm, respectively.

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