Hanoi records about 1682mm of rain across roughly 117 wet days a year, which is a 32% chance on an average day. August is the wettest month at 318mm (19% of the annual total) and January the driest at 18mm. Local rain type: monsoon. Pack quality rain gear for May through October — Hanoi monsoon rain is persistent and heavy. Winter (November-February) is dry but cool and often overcast.
Chance of rain on an average day: 32%
Rainfall climatology for Hanoi. The live hour-by-hour answer for today loads at the top of this page from Open-Meteo and refreshes through the day — the figures below describe a typical year, not today.
Last updated: · Live forecast data refreshes hourly.
| Annual rainfall | 1682mm |
| Rain days per year | 117 |
| Odds on an average day | 32% |
| Wettest month | August — 318mm over 22 days |
| Driest month | January — 18mm over 1 days |
| Rain type | monsoon |
| Best dry window | October through December offers the best weather — dry, cool, and comfortable for walking the Old Quarter. |
| Worst rain window | July and August bring the heaviest rain with occasional typhoon influence causing flooding. |
August delivers 1667% more rain than January (318mm vs 18mm). That gap is the difference between planning around showers and ignoring them.
No single month holds more than 19% of the annual total, so rain in Hanoi is spread through the year — there is no season you can rely on being dry.
Hanoi rain arrives in short, heavy bursts — shelter and timing matter more than gear.
Rain falls on about 22 days in August against 1 in January — the frequency swing matters more for planning than the millimetre totals.
Climate normals. Use them to judge whether today's live forecast at the top of the page is typical or unusual for the season.
| Month | Rainfall | Rain days | Chance on a given day | Highs |
|---|---|---|---|---|
| January | 18mm | 1 | 3% | 20°C |
| February | 26mm | 2 | 7% | 20°C |
| March | 44mm | 3 | 10% | 22°C |
| April | 90mm | 6 | 20% | 25°C |
| May | 189mm | 13 | 43% | 28°C |
| June | 240mm | 17 | 57% | 31°C |
| July | 288mm | 20 | 67% | 33°C |
| August | 318mm | 22 | 73% | 33°C |
| September | 265mm | 19 | 63% | 31°C |
| October | 131mm | 9 | 30% | 28°C |
| November | 43mm | 3 | 10% | 25°C |
| December | 23mm | 2 | 7% | 22°C |
Rain probability is the chance that at least 0.2mm falls at your location — not how long it rains. For Hanoi we combine the hourly probability curve, expected volume in millimetres, and the city's own rainfall record into a single umbrella verdict.
| Factor | Weight | What it measures |
|---|---|---|
| Hourly probability | 40% | Peak and sustained chance of measurable rain across the next 24 hours. |
| Expected volume | 30% | Total millimetres, which separates a passing shower from a genuine soaking. |
| Timing & duration | 20% | When rain starts, when it eases, and the longest continuous dry window. |
| Local rain type | 10% | Drizzle, brief showers, thunderstorms or monsoon — each needs different gear. |
Live hourly values come from Open-Meteo and refresh through the day. Monthly rainfall figures are climate normals, so they describe a typical year rather than a forecast.
Hanoi records rain on roughly 117 days a year — about a 32% chance on any given day — totalling around 1682mm.
August, with about 318mm over 22 rain days. That is 19% of the entire year's rainfall in a single month.
January is the driest month at 18mm across roughly 1 days. October through December offers the best weather — dry, cool, and comfortable for walking the Old Quarter.
Pack quality rain gear for May through October — Hanoi monsoon rain is persistent and heavy. Winter (November-February) is dry but cool and often overcast.
No. Probability is the chance that at least 0.2mm of rain falls at your location at some point in the period. Check the expected millimetres alongside it: 40% with 0.4mm is a passing shower, 40% with 12mm is a soaking.