Weather in Mumbai in September

A hard month. September is a hard month in Mumbai, and worth planning around. You should expect rain on 24 days of the month, which is more days wet than dry.

September ranks 8 of 12 in Mumbai: past the worst of the year but short of December, which is the month to book if the dates are open.

Rain on 24 of the month's 30 days, 11 of them heavy. At that frequency a wet-weather backup is not a contingency, it is the itinerary — book the indoor things first and treat the clear days as the bonus. Natural fibres and a second shirt for the day. At 89% nothing dries, including you.

What the averages hide

Averages flatten a month, and this one hides a few things: 11 days top 30 °C — hot spells arrive, but they break; the day barely swings — 5.2 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest September day reached 34.8 °C and the coldest night fell to 21.2 °C, and the wettest single day dropped 139 mm — roughly 37% of the month's rain in one day.

September is moderately variable: 90 mm in the driest year against 940 mm in the wettest, around an average of 376 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind is light at 8.3 km/h, so the temperature on the page is close to the temperature on your skin, and humidity at 89% is the real story though — it is the number that decides how the day feels, not the 29.8 °C.

How September sits in the year

Temperatures hold steady either side: 28.8 °C in August, 29.8 here, 31.9 in October. Nothing about the timing within the month matters much. Rain is the thing that moves: October brings 13 days less of it, so pushing the dates later buys drier weather.

Daylight in September

12.3 hours of daylight, losing 0.5 hours across the month. That is between Mumbai's extremes of 13.3 and 11 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 28.4 °C in September — warm enough that the water offers no relief from the heat. The sea peaks at 29.7 °C in May and bottoms out at 26.1 °C — water lags the air by a month or two, which is why the best swimming often comes after the best weather.

How busy it gets

Quiet. Few other visitors, cheaper rooms, and a real chance some seasonal operators are shut.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

September in Mumbai versus nearby

If Mumbai is one option among several, the nearby comparison is worth making. Virār is a better bet in September — within a degree on temperature, 2 days less rain. Pune is a better bet in September — 2.2 °C cooler, 2 days less rain.

So: September is a compromise. December is 33 points better and is what Mumbai is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Mumbai

See all twelve months in Mumbai, or where else to go in September.