Let us examine the significant monsoon patterns that typically occur in September. According to the official data from the Government of Pakistan, the average monthly rainfall varies between 11 mm and 30 mm. Nonetheless, there have been occasions where the precipitation surpassed the standard monthly range, resulting in heavy rainfall events in Karachi, notably in the years 2005, 2011, 2019, and most recently in 2021.

1. 2005 – What was classified as a “dry monsoon season” turned out to be only a temporary lull, as the rains came back with full force. Around 50 mm of rain in 24 hours (<80 mm in 48 hours) was recorded.
2. 2011 – No one can forget that year’s +1,000 mm of rain in the province during the monsoon season. The city recorded up to 140 mm of rain in 24 hours at PAF Base (official), an extreme rain event. It remains the wettest single-day rain in September to date.
3. 2019 – There were multiple spells in September. The first spell led to 40 mm of rain. Cyclone Hikaa left moisture for a low-pressure system over Gujarat-Rajasthan that caused heavy, stormy rain on September 27, 2019 (>100 mm of rain, an unofficial stat) in Karachi.
4. 2021 – There were several spells. The first caused around 68 mm of rain on September 3 in the city. Frequent rains towards the end unofficially made it the wettest September. 2021 witnessed one of the longest monsoon seasons due to Cyclone Shaheen in Karachi, extending into October.
5. 2025 – Two tropical systems affected the city. First, an ex-tropical storm, “Nongfa,” from the Pacific Ocean travelled a whopping 6,500 km, moving from the Philippines to Pakistan. Karachi received 130 mm (9th Sept, official stats from Surjani Town). Later, in September, would-be cyclone Shakhti in the Arabian Sea led to post-monsoon rains in Karachi, recorded at 33.4 mm at Old Karachi Airport on September 30.