| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 9.9° | — | 40.9mm | 5.7 | 56 |
| February | 11.1° | — | 68mm | 8.2 | 55 |
| March | 14.6° | — | 111.1mm | 10.3 | 62 |
| April | 19.7° | — | 162.1mm | 10.2 | 79 |
| May | 24.5° | — | 178.5mm | 10 | 80 |
| June | 27.3° | — | 228.5mm | 12.1 | 75 |
| July | 31° | — | 295.8mm | 12.7 | 59 |
| August | 33° | — | 143.7mm | 9 | 58 |
| September | 29.3° | — | 160.4mm | 9.3 | 72 |
| October | 23.8° | — | 106.8mm | 7.7 | 85 |
| November | 17.7° | — | 76.9mm | 7.1 | 78 |
| December | 12.3° | — | 61mm | 6.7 | 62 |
January in Hiroshima averages a daily high of 9.9°C. Expect roughly 5.7 wet days totalling 40.9mm. Generally workable, with some weather to plan around.
February in Hiroshima averages a daily high of 11.1°C. Expect roughly 8.2 wet days totalling 68mm. Generally workable, with some weather to plan around.
March in Hiroshima averages a daily high of 14.6°C. Expect roughly 10.3 wet days totalling 111.1mm. Generally workable, with some weather to plan around.
April in Hiroshima averages a daily high of 19.7°C. Expect roughly 10.2 wet days totalling 162.1mm. Comfortable conditions for being outdoors all day.
May in Hiroshima averages a daily high of 24.5°C. Expect roughly 10 wet days totalling 178.5mm. Comfortable conditions for being outdoors all day.
June in Hiroshima averages a daily high of 27.3°C. Expect roughly 12.1 wet days totalling 228.5mm. Comfortable conditions for being outdoors all day.
July in Hiroshima averages a daily high of 31°C. Expect roughly 12.7 wet days totalling 295.8mm. Generally workable, with some weather to plan around.
August in Hiroshima averages a daily high of 33°C. Expect roughly 9 wet days totalling 143.7mm. Generally workable, with some weather to plan around.
September in Hiroshima averages a daily high of 29.3°C. Expect roughly 9.3 wet days totalling 160.4mm. Generally workable, with some weather to plan around.
October in Hiroshima averages a daily high of 23.8°C. Expect roughly 7.7 wet days totalling 106.8mm. Comfortable conditions for being outdoors all day.
November in Hiroshima averages a daily high of 17.7°C. Expect roughly 7.1 wet days totalling 76.9mm. Comfortable conditions for being outdoors all day.
December in Hiroshima averages a daily high of 12.3°C. Expect roughly 6.7 wet days totalling 61mm. Generally workable, with some weather to plan around.
Each month scores out of 100. It starts at 100 and loses points for daytime highs outside a 20–27°C band, for wet days, and for nights below 2°C. Nothing else is weighted in — no crowd data, no prices, no opinion. Hiroshima peaks at 85.
Based on 30 years of records, April–May scores highest for comfort in Hiroshima, balancing daytime temperature against rainfall.
August is the warmest, averaging a daily high of 33°C.
July is the wettest, averaging 295.8mm of rain across roughly 12.7 wet days.
January is the coolest month, with average daily highs around 9.9°C.