Hiroshima is warmest in August, averaging 30° by day and 22° at night. The wettest month is July with 322 mm, and the year brings about 1768 mm in total.
Month by month
| Month | High | Low | Rain | Sea | Daylight | Good for |
|---|---|---|---|---|---|---|
| January | 8° | -2° | 65 mm | 13° | 9.9 h | Cool |
| February | 9° | -1° | 70 mm | 12° | 10.7 h | Cool |
| March | 14° | 1° | 121 mm | 12° | 11.7 h | Mild |
| April | 18° | 6° | 171 mm | 14° | 12.9 h | Mild |
| May | 22° | 11° | 186 mm | 18° | 13.8 h | Rainy season |
| June | 26° | 16° | 237 mm | 22° | 14.3 h | Rainy season |
| July | 29° | 21° | 322 mm | 26° | 14.1 h | Rainy season |
| August | 30° | 22° | 192 mm | 28° | 13.3 h | Rainy season |
| September | 27° | 17° | 168 mm | 26° | 12.2 h | Mild |
| October | 21° | 11° | 90 mm | 24° | 11.1 h | Sightseeing |
| November | 16° | 6° | 96 mm | 20° | 10.2 h | Sightseeing |
| December | 9° | 0° | 50 mm | 16° | 9.7 h | Cool |
High and low are average daily maximum and minimum, rain is typical monthly total, sea is the average surface temperature, daylight is the hours between sunrise and sunset mid-month. Climate normals from NASA POWER and NOAA MUR — averages, not promises.
When to go
Beach weather: No month in Hiroshima combines swimming warmth with dry skies.
Walking the city: October and November — highs of 16–21° and no more than 96 mm of rain a month.
Wet season: May, June, July and August — up to 322 mm in a single month.