Climate averages 1991–2020
Niihama weather
in December.
A cool, wet month: the 10th warmest and the joint 3rd driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a cool month in Niihama: daytime highs average 11.4°C and nights cool to about 5.5°C. By daytime temperature it is the 10th warmest of the 12 months.
Expect about 90 mm of rain on roughly 13 days, which makes December a wet month (the joint 3rd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 9 h 56 min on an average December day.
The nearest other city in this atlas is Saijō (12 km away). In December its highs average 11.3°C, about as warm as Niihama, with 90 mm of rain.
Among the 303 cities listed in Japan, Niihama ranks joint 39th of 303 for the warmest December highs and joint 247th of 303 for the driest December (rainfall, lowest first). The mean December high of those 303 cities is 9.5°C; Niihama is 1.9°C warmer than that mean.
From December to January, average highs fall by 2.4°C to 9.0°C, and monthly rainfall falls from 90 mm to 78 mm.
The annual picture
December in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Niihama climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 9.0°C3.3°C | 3.3°C | 78 | 13.5 | 10.210 h |
| February | 10.1°C3.3°C | 3.3°C | 86 | 12.3 | 10.911 h |
| March | 13.6°C5.8°C | 5.8°C | 122 | 13.4 | 12.012 h |
| April | 18.5°C10.4°C | 10.4°C | 134 | 11.6 | 13.013 h |
| May | 22.8°C15.1°C | 15.1°C | 158 | 11.2 | 13.914 h |
| June | 25.8°C19.5°C | 19.5°C | 249 | 15.1 | 14.414 h |
| July | 29.5°C23.9°C | 23.9°C | 228 | 15.6 | 14.214 h |
| August | 30.6°C24.8°C | 24.8°C | 151 | 13.8 | 13.413 h |
| September | 27.1°C21.4°C | 21.4°C | 216 | 14.1 | 12.412 h |
| October | 21.9°C15.7°C | 15.7°C | 166 | 11.0 | 11.411 h |
| November | 16.6°C10.2°C | 10.2°C | 90 | 9.9 | 10.410 h |
| December, selected | 11.4°C5.5°C | 5.5°C | 90 | 12.8 | 9.910 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
December in nearby cities
- Saijō in DecemberJapan · 12 kmHigh 11.3°C · Low 5.3°C · 90 mm rain
- Shikokuchūō in DecemberJapan · 23 kmHigh 11.1°C · Low 5.0°C · 93 mm rain
- Imabari in DecemberJapan · 31 kmHigh 11.0°C · Low 6.5°C · 79 mm rain
- Shinagawa in DecemberJapan · 45 kmHigh 9.7°C · Low 2.9°C · 84 mm rain
- Kochi in DecemberJapan · 50 kmHigh 11.7°C · Low 4.2°C · 90 mm rain
- Matsuyama in DecemberJapan · 52 kmHigh 11.3°C · Low 5.4°C · 83 mm rain
- Onomichi in DecemberJapan · 52 kmHigh 10.7°C · Low 3.8°C · 47 mm rain
- Mihara in DecemberJapan · 53 kmHigh 10.9°C · Low 3.6°C · 50 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Niihama) is explained once on the Niihama year overview and on the Sources, method and limits page.
Saijō lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.