Weather in Apia in September

A good month. September works. It is not the peak, but nothing about it fights you. You should expect rain on 17 days of the month, which is more days wet than dry.

Apia barely has seasons. September scores 64 out of 100 against a best of 72 in August — a gap small enough that the month you choose matters far less here than the week you choose.

This is persistent light rain rather than storms: 17 wet days but only 2 heavy ones. It rarely cancels anything outright, and it rarely fully clears either. A jacket beats an umbrella. Pack for 28.3 °C days and 26.5 °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: it never really gets hot: not one day in an average September reaches 30 °C; the day barely swings — 1.8 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest September day reached 29.8 °C and the coldest night fell to 23.7 °C, and the wettest single day dropped 59 mm — roughly 64% of the month's rain in one day.

September is moderately variable: 5 mm in the driest year against 178 mm in the wettest, around an average of 92 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind sits around 19.4 km/h — a steady breeze rather than a nuisance, and welcome on the warmer days, and humidity runs at 79%, high enough to notice on the warm days without dominating them.

How September sits in the year

Temperatures hold steady either side: 28 °C in August, 28.3 here, 28.5 in October. Nothing about the timing within the month matters much. Rain is the thing that moves: October brings 5 days more of it, so the earlier half of a flexible trip is the safer half.

Daylight in September

Apia sits close enough to the equator that daylight barely moves all year — 12 hours in September, against a range of just 1.6 hours across the whole calendar. Sunrise and sunset land at roughly the same time whenever you come.

Sea temperature

The sea sits at about 27.8 °C in September — warm enough that the water offers no relief from the heat. The sea peaks at 29.5 °C in March and bottoms out at 27.8 °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

Shoulder. The value months — prices ease off and you get the place closer to itself. September is the value pick for Apia: it scores within 8 points of August without carrying August's prices.

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

September in Apia versus nearby

If Apia is one option among several, the nearby comparison is worth making. Nuku‘alofa is a better bet in September — 5 °C cooler, 5 days less rain. Avarua is a better bet in September — 4.5 °C cooler, 3 days less rain.

So: September works, with August the better month by 8 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Apia

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