Weather in Manaus in September

A hard month. September is a hard month in Manaus, and worth planning around. Highs average 33.1 °C, lows 25.8 °C, and rain falls on 14 days — nothing in the month is working against you.

September ranks 9 of 12 in Manaus: past the worst of the year but short of August, which is the month to book if the dates are open.

This is persistent light rain rather than storms: 14 wet days but only 1 heavy ones. It rarely cancels anything outright, and it rarely fully clears either. A jacket beats an umbrella. Pack for 33.1 °C days and 25.8 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: 7 days clear 35 °C, so a serious heatwave is normal rather than notable. Across the twenty years measured, the hottest September day reached 40.6 °C and the coldest night fell to 23.3 °C, and the wettest single day dropped 38 mm — roughly 56% of the month's rain in one day.

September is moderately variable: 10 mm in the driest year against 125 mm in the wettest, around an average of 68 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind is light at 2.5 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 72%.

How September sits in the year

Temperatures hold steady either side: 31 °C in August, 33.1 here, 33.1 in October. Nothing about the timing within the month matters much.

Daylight in September

Manaus sits close enough to the equator that daylight barely moves all year — 12.1 hours in September, against a range of just 0.4 hours across the whole calendar. Sunrise and sunset land at roughly the same time whenever you come.

An inland climate

Despite being inland, the year stays fairly even: 8.9 °C between the year's warmest afternoons and coldest nights.

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 Manaus versus nearby

If Manaus is one option among several, the nearby comparison is worth making. Belém is close enough to be a coin toss — within a degree on temperature, 2 days more rain. Cusco is a better bet in September — 14.7 °C cooler, 9 days less rain.

So: September works, with August the better month by 12 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Manaus

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