Climate averages 1991–2020
Jōetsu weather
by month.
See how the year changes. August has the highest average daily maximum; May has the lowest average monthly rainfall.
Long-term climate patterns, not a forecast for a particular trip.
Across the year Jōetsu averages a daytime high of 16.7°C and a nighttime low of 9.4°C, with about 1,949 mm of rain on roughly 202 days. August is the warmest month (average high 29.3°C) and January the coolest (4.1°C). January is the wettest month with 254 mm; May is the driest with 92 mm.
The annual picture
A year in Jōetsu
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
Jōetsu climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 4.1°C-1.1°C | -1.1°C | 254 | 26.0 | 9.910 h |
| February | 4.6°C-1.3°C | -1.3°C | 179 | 21.4 | 10.811 h |
| March | 8.3°C0.6°C | 0.6°C | 145 | 19.6 | 11.912 h |
| April | 15.2°C5.4°C | 5.4°C | 97 | 13.4 | 13.113 h |
| May | 21.0°C11.5°C | 11.5°C | 92 | 11.6 | 14.114 h |
| June | 24.4°C16.4°C | 16.4°C | 115 | 11.5 | 14.715 h |
| July | 27.8°C20.9°C | 20.9°C | 191 | 14.4 | 14.414 h |
| August | 29.3°C22.2°C | 22.2°C | 122 | 12.1 | 13.614 h |
| September | 25.2°C18.4°C | 18.4°C | 162 | 14.1 | 12.512 h |
| October | 19.6°C12.4°C | 12.4°C | 164 | 15.1 | 11.311 h |
| November | 13.7°C6.4°C | 6.4°C | 180 | 18.5 | 10.210 h |
| December | 7.4°C1.2°C | 1.2°C | 247 | 24.2 | 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
Nearby cities
- KashiwazakiJapan · 37 kmHigh 16.9°C · Low 9.1°C · 1,898 mm rain a year
- NaganoJapan · 56 kmHigh 15.4°C · Low 6.9°C · 1,842 mm rain a year
- NagaokaJapan · 64 kmHigh 16.9°C · Low 8.5°C · 1,701 mm rain a year
- SanjōJapan · 82 kmHigh 16.8°C · Low 8.7°C · 1,964 mm rain a year
- UedaJapan · 83 kmHigh 16.3°C · Low 7.3°C · 1,520 mm rain a year
- TsubameJapan · 84 kmHigh 16.5°C · Low 9.5°C · 1,702 mm rain a year
- ShibukawaJapan · 100 kmHigh 17.0°C · Low 8.8°C · 1,588 mm rain a year
- AzuminoJapan · 101 kmHigh 15.4°C · Low 6.5°C · 1,896 mm rain a year
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 limitsWhat do the high and low temperatures mean?
We average the daily maximum and daily minimum for each calendar month over 1991–2020. They are not record extremes, a forecast range or temperatures at a fixed time of day.
How is a rain day counted?
A local calendar day (standard time, UTC+9, no daylight saving) with at least 1 mm of total precipitation counts as one rain day. We count these for each year and month, then average across 30 years. The average does not predict which days will be wet.
Where do the numbers come from?
ERA5-Land (temperature) and ERA5 (precipitation) reanalysis from the Copernicus Climate Change Service, read from the Open-Meteo open-data archive. Temperature comes from the 0.1° model cell at 37.10°, 138.20° (6 km from the city centre), adjusted up by 1.0°C for the difference between the city's elevation (10 m) and the cell's (166 m). Rain comes from the 0.25° cell at 37.25°, 138.25°. These are model estimates, not weather-station readings; coast, hills and city streets can differ.
Does this page show sunshine, humidity or sea temperature?
No. The data used here contain air temperature and precipitation only. Daylight hours are calculated from the city's latitude (sunrise to sunset), not measured sunshine.