Weather in Nha Trang in September

Shoulder season. September is shoulder season in Nha Trang — cheaper, quieter, and a genuine gamble. You should expect rain on 26 days of the month, which is more days wet than dry.

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

Rain on 26 of the month's 30 days, 7 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 82% nothing dries, including you.

What the averages hide

Averages flatten a month, and this one hides a few things: 7 days top 30 °C — hot spells arrive, but they break; 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 31.5 °C and the coldest night fell to 25.9 °C, and the wettest single day dropped 97 mm — roughly 44% of the month's rain in one day.

September is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest September on record still delivered 482 mm against 100 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 220 mm average is a reasonable planning figure, not a promise.

Wind is light at 11.8 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 82%, high enough to notice on the warm days without dominating them.

How September sits in the year

Temperatures hold steady either side: 29.7 °C in August, 29.4 here, 28.4 in October. Nothing about the timing within the month matters much.

Daylight in September

Nha Trang sits close enough to the equator that daylight barely moves all year — 12.2 hours in September, against a range of just 1.4 hours across the whole calendar. Sunrise and sunset land at roughly the same time whenever you come.

Sea temperature

The sea sits at about 29.2 °C in September — warm enough that the water offers no relief from the heat. The sea peaks at 29.3 °C in May and bottoms out at 25.3 °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

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

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

September in Nha Trang versus nearby

If Nha Trang is one option among several, the nearby comparison is worth making. Qui Nhon is close enough to be a coin toss — within a degree on temperature, 3 days less rain. Vũng Tàu is close enough to be a coin toss — within a degree on temperature, the same number of rain days.

So: September is a compromise. February is 41 points better and is what Nha Trang 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 Nha Trang

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