Weather in Hiroshima in December

A hard month. December is a hard month in Hiroshima, and worth planning around. Highs sit at 10.6 °C and the day is short; this is an indoors-with-excursions month, not an outdoors-all-day one.

December ranks 10 of 12 — near the bottom of Hiroshima's year. October is the month that works, and the swing between the two is 38 points, which is a different holiday rather than a slightly better one.

Rain on 12 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Layers, and a genuinely waterproof outer — at 10.6 °C the difference between a good day and a miserable one is entirely down to what you are wearing.

What the averages hide

Averages flatten a month, and this one hides a few things: 6 nights fall below freezing. Across the twenty years measured, the hottest December day reached 23.1 °C and the coldest night fell to -3.7 °C, and the wettest single day dropped 84 mm — roughly 100% of the month's rain in one day.

December is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest December on record still delivered 136 mm against 28 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 84 mm average is a reasonable planning figure, not a promise.

Wind is light at 8.1 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 85%, which at 10.6 °C means damp rather than muggy — the kind of cold that gets into a coat and stays there.

How December sits in the year

The month is on the way down: 6.2 °C cooler than November, with January dropping another 2.4 °C. The first week and the last are not the same trip.

Daylight in December

December sits at the dark end of Hiroshima's year — 9.9 hours of daylight against 14.4 at midsummer, holding steady all month. Sightseeing days are genuinely shorter, and an itinerary built for summer will not fit.

Sea temperature

The sea sits at about 16.9 °C in December — cold — a quick dip rather than a swim, and a wetsuit if you are in for longer. The sea peaks at 26.9 °C in August and bottoms out at 12.9 °C — water lags the air by a month or two, which is why the best swimming often comes after the best weather.

How busy it gets

Quiet. Few other visitors, cheaper rooms, and a real chance some seasonal operators are shut.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

December in Hiroshima versus nearby

If Hiroshima is one option among several, the nearby comparison is worth making. Kitakyushu is close enough to be a coin toss — within a degree on temperature, 1 day less rain. Fukuoka is close enough to be a coin toss — within a degree on temperature, 2 days less rain.

So: December is a compromise. October is 33 points better and is what Hiroshima is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Hiroshima

See all twelve months in Hiroshima, or where else to go in December.