Vietnam Weather in September

Although the weather of Vietnam during September remains hot, it has subsided to an acceptable level. Rainfall, though still significant, exhibits a gradual downward trend. The picturesque rural scenery during the harvest season and the humanistic atmosphere of the characteristic festivals overlap at this time, making September a decent period for a visit before the peak tourist season in Vietnam.

Temperature

In September, although maximum temperatures in most places of Vietnam remain high, the climate has become relatively cool outside of midday hours.

For example, in Hanoi, the capital city in northern Vietnam, the nighttime lows range from 24 to 27 degrees Celsius (75 to 81 degrees Fahrenheit), while daytime highs typically between 32 and 35℃ (90 to 95℉). Although outdoor activities during daytime hours may still make you sweat, early morning walks or evening visits to night markets offer a relatively comfortable experience, with light breezes providing a refreshing respite.

In the south, for instance, Ho Chi Minh City, the low temperatures range from 24 to 26℃ (75 to 79℉), and the high temperatures range from 30 to 34℃ (86 to 93℉). With the moisture brought by the monsoon, you will still feel muggy. Even a slight movement will make your hair damp with sweat and stick to your face. However, when there is no direct sunlight, you will indeed feel a bit cool.

Unlike other places, Sapa in September is exceptionally cool. Thanks to its high altitude, the temperature here remains stable between 23 and 31℃ (73 to 88℉), like a natural air-conditioned room. The mountain wind carries a hint of coolness; at night, you may even need a long-sleeved shirt for warmth when going out.

Hanoi Vegetable Market

Street Cafe in Saigon

Precipitation

Average precipitation: 314 mm from 17 rainy days

In September, the rainfall in Vietnam remains relatively high, but it gradually decreases as the southwest monsoon weakens. For instance, in Hanoi, the total rainfall in the month is 265 mm, with an average of about 14 rainy days. The rain mostly come in intermittent showers, sometimes stopping within just a few minutes. Overall, it does not significantly affect travel plans.

Typhoon Season

September is the peak period of typhoons, and they occasionally bring prolonged heavy rainfall. In September 2025, two typhoons affected Vietnam: Typhoon “Ragasa” entered northern Vietnam with Quang Ninh Province at its core on September 25th, bringing 100 to 300 mm of rainfall; Typhoon “Bualoi” made landfall in Ha Tinh Province in the central region on September 29th, with widespread rainfall of over 300 mm. These also led to continuous heavy rain in Hanoi, which grew increasingly intense, with water levels on the streets reaching up to the thighs.

Therefore, when traveling in September, it is crucial to monitor typhoon forecasts in advance and try to avoid the periods when typhoons are predicted to hit. Otherwise, you may not only encounter flight delays and restrictions on outdoor activities, but also face safety risks such as floods and geological disasters.