Hanoi Weather in September
Vietnam · Humid Subtropical climate · Data averaged from 2020-01-01 to 2024-12-31 (5 years)
September in Hanoi sees average temperatures ranging from a low of 24.9°C (76.8°F) to a high of 30.7°C (87.3°F), with a mean of 27.4°C (81.3°F). Compared to the annual average of 24.3°C (75.7°F), this month is 3.1°C warmer than the yearly norm. Precipitation averages 434.3mm, making it approximately 253.0mm wetter than the monthly average of 181.0mm. This is the wettest month of the year, with 434.3mm of precipitation and around 25.6 rainy days. The city receives an average of 7.4 hours of sunshine per day during September, with relative humidity averaging 85.9%. Wind speeds reach an average maximum of 14.2 km/h. For travelers, this month offers a temperature experience in Hanoi, with wetter-than-average conditions compared to the rest of the year.
Hanoi taught me that 'winter' in Southeast Asia is relative — but still real. I arrived in January in a t-shirt and shivered through 14°C with 85% humidity. That damp cold cuts through layers in a way the thermometer doesn't capture. Pack a fleece and light jacket November-February. The nightmare window is June-August: 33°C, 80% humidity, and downpours that flood the Old Quarter streets. May and October are the smart traveler's picks: 27°C, lower humidity, manageable rain. Always carry a compact umbrella year-round — Hanoi averages 1600mm and the rain comes fast.
September vs Adjacent Months
| Metric | August | September | October |
|---|---|---|---|
| Mean Temp | 28.6°C (83.5°F) | 27.4°C (81.3°F) | 24.5°C (76.1°F) |
| Rainfall | 386.1mm | 434.3mm | 215.9mm |
| Sunshine | 8.3 hrs | 7.4 hrs | 7.5 hrs |
| Humidity | 85.5% | 85.9% | 76.2% |
| Wind | 13.5 km/h | 14.2 km/h | 15.8 km/h |
| Rainy Days | 27.6 | 25.6 | 16.0 |
Seasonal Context
September falls in Autumn in the Northern Hemisphere. Autumn sees temperatures gradually cooling from summer highs. For travelers visiting Hanoi in September, the data indicates mixed conditions based on the combination of temperature, precipitation, and daylight hours.
Frequently Asked Questions
What is the average temperature in Hanoi in September?
The average temperature in Hanoi during September ranges from 24.9°C (76.8°F) to 30.7°C (87.3°F), with a mean of 27.4°C (81.3°F).
How much does it rain in Hanoi in September?
Hanoi receives an average of 434.3mm of precipitation in September, spread across approximately 25.6 rainy days. This is the wettest month of the year.
What should I pack for Hanoi in September?
Based on September weather data, pack lightweight, breathable clothing, sunscreen, and a hat. Rain gear is essential — this month averages 434.3mm of precipitation.
Is September a good time to visit Hanoi?
September is a month with challenging conditions. Plan activities carefully and stay hydrated.
Other Months for Hanoi
Cities with Similar September Climate (Humid Subtropical)
Data Source: Open-Meteo historical archive (2020-01-01 to 2024-12-31). Daily measurements aggregated into monthly climate normals. Coordinates: 21.03°, 105.85°. Timezone: Asia/Ho_Chi_Minh. Last updated: 2026-07-30.