September is the least rainiest monsoon month for Mumbai. Average monthly rainfall based on 30 years data (1990-2020) stands at 383.5mm. However, the variability is very large in the closing month of monsoon. In September 2018, the city failed to reach even 3 digit mark and measured only 73.1mm rainfall. On the contrary, Sep 2019 was the rainiest on record with 1115.7mm. Though, the monsoon season is accounted for till 30thSep, Mumbai continues with retreating monsoon showers till 15thOct and sometimes even later.
Opening days of September have experienced mostly light and patchy rains, except day before when Santacruz recorded 94mm of rainfall. However, Colaba observatory measured single digit 24hr rainfall. Earlier, July had scored over 1000mm rainfall but August was a dampener with below normal rains. A decent spell of rains is likely to come up for the capital city Mumbai, anytime soon.
Rains will be just light and patchy for the next 2 days, on 05th and 06thSep. Later, the trough along the West Coast will find extension up to Konkan and Mumbai. Light shower, interspersed with moderate spells are expected on 07thSep. A cyclonic circulation and a low pressure area/ depression is likely to come up over central parts of Bay of Bengal. This weather feature will reach the East Coast on 08thSep, with an east-west oriented trough extending across Maharashtra up to Mumbai. Over the next 3 days, the weather system will travel across Chhattisgarh, Maharashtra, Gujarat and Rajasthan. This system is going to spend more time over North Madhya Maharashtra and Gujarat. Moderate to heavy rains are likely over Mumbai between 08th and 12th September. Intensity and spread of weather activity will be more between 09th and 11thsep. During this wet spell, city may receive as much as 200 mm of rainfall.
Low pressure area is expected to shift across parts of Rajasthan, travelling south to north. Rainfall belt will also shift accordingly. Moderate showers may continue over the financial capital between 12thand 14th Sep and find clearance 15th onward.