Weather in Hanoi

Hanoi is in Vietnam at 21.0°N. The 2001–2020 NASA POWER daily record describes a monsoon climate with a sharp wet-dry split. Rain is the monsoon runs from May to October, inside an annual total of 1607 mm. The wettest month is August at 322 mm; the driest is February at 22 mm.

June is the warmest month (average 28.9°C, high 32.3°C) and January is the coolest (average 16.0°C, low 11.1°C). From the coolest night in January (11.1°C) to the hottest afternoon in June (32.3°C), the raw range is 21.2°C. On this site the months that score closest to a 22°C day, lighter rain, and moderate humidity are February, March, and December.

Monsoon and dry months

The monsoon in Hanoi starts in May and ends in October (May, June, July, August, September, and October). August is the core of it at 322 mm. February is the other extreme, with 22 mm.

A rainy day here is a day with at least 1 mm in the NASA POWER series. August averages 24 such days; February averages 6.

Temperature through the year

Monthly average highs run from 20.8°C in January to 32.3°C in June. Nights follow the same curve: 11.1°C in January and 25.4°C in June.

Mean high across all twelve months is 28.0°C and mean low is 19.4°C. These are 20-year grid averages, so a city station can read a few degrees warmer or cooler.

Distinctive months in Hanoi

January is the coolest month, with lows around 11.1°C and highs near 20.8°C. Rainfall is 32 mm. February is the driest month, averaging only 22 mm across 6 rainy days. Highs sit near 24.1°C. March stands apart from the months beside it: 27.3°C / 16.9°C and 49 mm. April: 31.0°C high, 20.6°C low, 78 mm rain, 78% humidity. May is when the monsoon typically starts in Hanoi: highs near 32.2°C, and rainfall jumps to 179 mm (18 rainy days). Peak heat arrives in June: 32.3°C by day, 25.4°C at night, and 84% humidity.

July stands apart from the months beside it: 32.0°C / 25.4°C and 300 mm. August is the wettest month — 322 mm and 24 rainy days, with 86% humidity. In September, Hanoi averages 30.4°C by day and 23.4°C at night, with 223 mm of rain. October closes the monsoon: 124 mm over 11 rainy days, then the calendar dries. November: 25.0°C high, 16.1°C low, 52 mm rain, 82% humidity. December stands apart from the months beside it: 21.1°C / 11.5°C and 25 mm.

Best months to visit Hanoi

The three months with the highest comfort score are February, March, and December: February (18.9°C average, 22 mm, 80% humidity); March (22.1°C average, 49 mm, 80% humidity); December (16.3°C average, 25 mm, 80% humidity). They fall in calendar order. The score rewards averages near 22°C, lower rainfall, and humidity near 60%. It is a climate score, not a festival or price calendar.

If you want the monsoon itself — fewer crowds, greener landscape, heavier rain — aim at May–October instead of the score.

How Hanoi compares inside Vietnam

Haiphong is about 89 km away: Hanoi is about as warm as Haiphong at the hot peak and a similar annual rainfall (1643 mm in Haiphong). Haiphong’s wettest month is August (338 mm) versus August here.

Huế is about 540 km away: Hanoi is about as warm as Huế at the hot peak and 554 mm drier over the year than Huế. Huế’s wettest month is October (560 mm) versus August here.

Da Nang is about 606 km away: Hanoi is about as warm as Da Nang at the hot peak and 603 mm drier over the year than Da Nang. Da Nang’s wettest month is October (562 mm) versus August here.