Climate averages 1991–2020
Koga weather
in December.
A cool, moderately wet month: the 10th warmest and the driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a cool month in Koga: daytime highs average 10.0°C and nights cool to about 0.7°C. By daytime temperature it is the 10th warmest of the 12 months.
Expect about 54 mm of rain on roughly 7 days, which makes December a moderately wet month (the driest month of the year). Daylight, from sunrise to sunset, lasts about 9 h 45 min on an average December day.
The nearest other city in this atlas is Kazo (13 km away). In December its highs average 10.3°C, about as warm as Koga, with 49 mm of rain.
Among the 303 cities listed in Japan, Koga ranks joint 179th of 303 for the warmest December highs and joint 33rd of 303 for the driest December (rainfall, lowest first). The mean December high of those 303 cities is 9.5°C; Koga is 0.6°C warmer than that mean.
From December to January, average highs fall by 2.4°C to 7.6°C, and monthly rainfall rises from 54 mm to 55 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
Koga climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 7.6°C-2.1°C | -2.1°C | 55 | 6.0 | 10.010 h |
| February | 8.8°C-1.3°C | -1.3°C | 55 | 6.9 | 10.811 h |
| March | 12.5°C1.9°C | 1.9°C | 106 | 11.6 | 11.912 h |
| April | 17.7°C7.1°C | 7.1°C | 120 | 12.6 | 13.113 h |
| May | 22.3°C12.6°C | 12.6°C | 153 | 13.7 | 14.114 h |
| June | 25.0°C17.2°C | 17.2°C | 177 | 16.5 | 14.615 h |
| July | 28.4°C21.3°C | 21.3°C | 209 | 18.7 | 14.414 h |
| August | 29.8°C22.6°C | 22.6°C | 161 | 16.3 | 13.514 h |
| September | 26.0°C19.2°C | 19.2°C | 206 | 16.2 | 12.412 h |
| October | 20.5°C13.0°C | 13.0°C | 200 | 13.9 | 11.311 h |
| November | 15.2°C6.3°C | 6.3°C | 88 | 9.4 | 10.310 h |
| December, selected | 10.0°C0.7°C | 0.7°C | 54 | 6.8 | 9.710 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
- Kazo in DecemberJapan · 13 kmHigh 10.3°C · Low 0.8°C · 49 mm rain
- Kukichūō in DecemberJapan · 13 kmHigh 10.3°C · Low 0.8°C · 52 mm rain
- Oyama in DecemberJapan · 15 kmHigh 9.7°C · Low 0.4°C · 54 mm rain
- Tatebayashi in DecemberJapan · 18 kmHigh 9.8°C · Low 0.7°C · 51 mm rain
- Sano in DecemberJapan · 19 kmHigh 9.8°C · Low 0.5°C · 51 mm rain
- Kōnosu in DecemberJapan · 22 kmHigh 10.2°C · Low 0.9°C · 49 mm rain
- Tochigi in DecemberJapan · 22 kmHigh 9.5°C · Low 0.4°C · 55 mm rain
- Kasukabe in DecemberJapan · 22 kmHigh 10.5°C · Low 1.1°C · 52 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 Koga) is explained once on the Koga year overview and on the Sources, method and limits page.
Oyama lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.