Hiroshima records about 1537mm of rain across roughly 100 wet days a year, which is a 27% chance on an average day. July is the wettest month at 235mm (15% of the annual total) and January the driest at 42mm. Local rain type: monsoon. Hiroshima gets heavy June-July rain from the Baiu front. The Peace Memorial Museum is the most meaningful rainy-day destination imaginable.
Chance of rain on an average day: 27%
Rainfall climatology for Hiroshima. 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 | 1537mm |
| Rain days per year | 100 |
| Odds on an average day | 27% |
| Wettest month | July — 235mm over 17 days |
| Driest month | January — 42mm over 3 days |
| Rain type | monsoon |
| Best dry window | October through December offers comfortable, dry weather. |
| Worst rain window | June and July bring the heaviest rain as the Baiu front stalls over the region. |
July delivers 460% more rain than January (235mm vs 42mm). That gap is the difference between planning around showers and ignoring them.
No single month holds more than 15% of the annual total, so rain in Hiroshima is spread through the year — there is no season you can rely on being dry.
Hiroshima rain arrives in short, heavy bursts — shelter and timing matter more than gear.
Rain falls on about 17 days in July against 3 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 | 42mm | 3 | 10% | 10°C |
| February | 55mm | 4 | 13% | 10°C |
| March | 102mm | 7 | 23% | 13°C |
| April | 118mm | 9 | 30% | 19°C |
| May | 148mm | 11 | 37% | 24°C |
| June | 232mm | 17 | 57% | 30°C |
| July | 235mm | 17 | 57% | 33°C |
| August | 112mm | 8 | 27% | 33°C |
| September | 148mm | 11 | 37% | 30°C |
| October | 82mm | 6 | 20% | 24°C |
| November | 58mm | 4 | 13% | 19°C |
| December | 42mm | 3 | 10% | 13°C |
Rain probability is the chance that at least 0.2mm falls at your location — not how long it rains. For Hiroshima 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.
Hiroshima records rain on roughly 100 days a year — about a 27% chance on any given day — totalling around 1537mm.
July, with about 235mm over 17 rain days. That is 15% of the entire year's rainfall in a single month.
January is the driest month at 42mm across roughly 3 days. October through December offers comfortable, dry weather.
Hiroshima gets heavy June-July rain from the Baiu front. The Peace Memorial Museum is the most meaningful rainy-day destination imaginable.
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.