Question 1

When is the rainy season in Hanoi and which months are the wettest?

Accepted Answer

Hanoi's rainy season runs from May to September, when the city receives the bulk of its annual rainfall thanks to the summer monsoon. In 2025, these five months alone delivered 1,659mm (65.3in) of rain, roughly 73% of the city's total annual precipitation of 2,265mm (89.2in).

The wettest months in Hanoi during 2025 were concentrated in mid-to-late summer:

- **August:** 399mm (15.7in) — the single wettest month
- **June:** 388mm (15.3in)
- **September:** 346mm (13.6in)

May also stood out with 253mm (10.0in), marking the sharp start of the wet season as temperatures climbed into the high 20s°C (low 80s°F). These months combine heavy, often short-lived downpours with high humidity that averaged above 83% across the summer.

By contrast, Hanoi's dry season from November to March is strikingly different. Those months together totaled just 260mm (10.2in) of rain in 2025, about 11% of the yearly total. January was the driest month of all, with only 22mm (0.9in).

For travelers, this means the cooler, drier window from late autumn through early spring is the most comfortable time to explore Hanoi on foot, while visits between May and September should factor in sudden tropical rain. Carrying a compact umbrella and planning flexible itineraries makes the city's wet season far more manageable, especially during the peak downpours of June, August, and September.

Question 2

How hot does Hanoi get in summer?

Accepted Answer

Hanoi gets hot and intensely humid in summer, averaging **28.6°C (83.4°F)** across the meteorological summer of 2025 (June 1 to August 31), with temperatures peaking at **37.9°C (100.2°F)** in June.

July was the warmest month of 2025 in Hanoi, with a mean temperature of **28.8°C (83.8°F)**, closely followed by June at 28.7°C (83.7°F) and August at 28.2°C (82.8°F). Each of these three months saw peak readings near or above 37°C (99°F), so daytime highs regularly pushed into the mid-to-upper 30s°C (mid-to-upper 90s°F). Even overnight there was little relief, as the average summer low stayed warm at **23.8°C (74.9°F)**.

What makes Hanoi feel especially sweltering is the humidity, which averaged **84.5%** during the summer of 2025 and pushed the "feels-like" temperature well above the thermometer reading. This moisture also fuels heavy monsoon rainfall, with June through August delivering more than 1,000 mm (39 inches) of precipitation combined.

For visitors, this means summer in Hanoi calls for light, breathable clothing, plenty of water, and a plan to seek air-conditioned shade during the midday heat. Outdoor sightseeing is most comfortable in the early morning or evening, when temperatures ease slightly and the harsh midday sun has passed.

Question 3

How cold does Hanoi get in winter, and which are the coolest months?

Accepted Answer

Hanoi has a mild, dry winter, with the coolest stretch falling in Winter 2024/25 (December 2024 to February 2025). During the portion within 2025 (January–February), the city averaged a comfortable 17.6°C (63.6°F), making this the coolest period of the year.

February 2025 was the single coolest month, with a mean temperature of 17.3°C (63.1°F), narrowly cooler than January's 17.8°C (64.0°F). Even so, Hanoi rarely turns truly cold: the lowest monthly low of the whole year occurred in January 2025 at 8.1°C (46.6°F), while daytime highs across January and February still averaged a pleasant 26.9°C (80.4°F).

The cool season is also Hanoi's driest spell. January 2025 saw just 22.1mm (0.87in) of rain and the lowest humidity of the year at 66%, alongside 184 hours of sunshine. February turned greyer, with only 23 hours of sunshine and humidity climbing to 81%, reflecting the misty "drizzle season" Hanoi is known for in late winter.

For visitors, these conditions make winter one of the most agreeable times to explore Hanoi. The mild temperatures and limited rainfall are ideal for walking the Old Quarter or sightseeing around Hoan Kiem Lake, though a light jacket is worth packing for chilly mornings when temperatures can dip toward 8–10°C (46–50°F).

Question 4

What is the sunniest time of year in Hanoi?

Accepted Answer

The sunniest time of year in Hanoi is summer, from June to August, when long daylight hours and high sun angles deliver the city's brightest skies. In 2025, this stretch easily outshone every other season despite coinciding with the rainy period.

Across 2025, Hanoi recorded about 2,354.8 hours of sunshine, averaging roughly 6.5 hours per day. The summer months (June–August 2025) alone accounted for 830.3 of those hours, with July the single sunniest month at 288.8 hours — close to 9.3 hours of sunshine per day. June (278.7 hours) and August (262.8 hours) followed closely behind, keeping the whole season consistently bright. Temperatures during this peak were warm, with July averaging 28.8°C (83.8°F).

By sharp contrast, February 2025 was the gloomiest month by far, with just 23.0 hours of sunshine — under one hour per day — reflecting Hanoi's well-known late-winter drizzle and overcast skies.

If maximizing sunshine is your priority, the summer months offer the most reliable brightness, though you should plan around frequent afternoon downpours and high humidity. For sunshine paired with drier, cooler conditions, early autumn in Hanoi (September to October) is a strong alternative, still delivering well over 190 hours of sun per month in 2025 with more comfortable temperatures.

Question 5

What is the weather like in Hanoi in October?

Accepted Answer

October is one of the most comfortable months to visit Hanoi, marking the transition from the hot, wet summer monsoon into the cooler, drier autumn. In October 2025, Hanoi had a pleasant average temperature of 25.3°C (77.5°F).

Daytime highs in October 2025 averaged around 33.0°C (91.4°F), while cooler nights dropped to about 18.2°C (64.8°F) — a noticeably wider day-to-night spread than the muggy summer months. The month still saw meaningful rainfall, with 228.5mm (9.0 in) of precipitation, though this was already well down from August's peak of nearly 400mm. Average humidity eased to 80.9%, and Hanoi enjoyed roughly 194 hours of sunshine, or about 6.3 hours of sun per day.

Overall, October represents a clear turning point in Hanoi's weather: mean temperatures fell 2.5°C from September and dropped a further 5.1°C heading into November 2025. Winds stayed gentle at around 7.9 km/h (4.9 mph).

These conditions make October a strong choice for sightseeing and walking around Hanoi's Old Quarter and lakes — warm but no longer oppressive, with more sunshine and steadily easing rain. Just pack a light layer for the cooler evenings and a compact umbrella, since occasional autumn showers are still possible in this part of the season.

Đinh Công Hạ

Hanoi

FAQ

When is the rainy season in Hanoi and which months are the wettest?

How hot does Hanoi get in summer?

How cold does Hanoi get in winter, and which are the coolest months?

What is the sunniest time of year in Hanoi?

What is the weather like in Hanoi in October?