Monsoon is always welcomed by Mumbaikars but heavy rains, water logging puts Mumbai life on halt. As per by India Meteorological Department (IMD), the newly updated since 2020, the monsoon onset dates are revised and the onset is changed. The new normal date of Mumbai is 15th June instead of 10th June. Last year in 2019 monsoon was onset over Mumbai on 25th June.
By IMD, the normal dates of monsoon onset have been revised based on data during the 1961-2019 period. The normal dates of withdrawal have been revised based on data from 1971 to 2019.
The average seasonal rain that is rainfall from June to September is:
1) Santacruz is 2265 mm.
2) Colaba is 2025 mm.
Mumbai Monsoon Onset Dates
Here are some statistics for onset dates over Mumbai:
1) Early-onset – 29th May in the year 1952, 1956, 1872
2) Late-onset – 25th June in 1962
Below is the chart of monsoon dates over Mumbai for last 67 years till 2018. (Data source: IMD)
(Click the image to see enlarge image)
EXTREME RAINFALL EVENTS OF MUMBAI
The highest rainfall recorded over Mumbai in the month of June is 478 mm. The 944 mm is the highest ever recorded in July.
Here are some facts about rainfall during the period of June to September.
The normal date of monsoon over Mumbai is 10th June, but the dates had been fluctuating. In some years the monsoon was delayed considerably while in some years it had been very early.
The extreme rainfall events in Mumbai:
| Colaba | 10 June 1991 478 mm | 5 July 1974 576 mm | 3 Aug 1881 287 mm | 10 Sept 1930 548 mm |
| Santacruz | 10 June 1991 399 mm | 27 July 2005 944 mm | 23 Aug 1997 346 mm | 23 Set 1981 318 mm |