Jōetsu weather in August
In August, Jōetsu has daytime highs averaging 29 °C, nights around 22 °C, with 18 wet days, and a sea temperature of 27 °C. Figures are 1991–2020 climate normals.
- 29.2°C Average high
- 22.4°C Average low
- 18days Wet days
- 196mm Rainfall
- 26.6°C Sea temperature
- 14h Daylight
Daily temperatures through August
How August develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 August | 30.0 °C | 22.9 °C | 56 % |
| 11–20 August | 29.4 °C | 22.5 °C | 58 % |
| 21–31 August | 28.3 °C | 21.7 °C | 65 % |
- Average highs fall from 30.0 °C early in August to 28.3 °C by the end of it.
- Rain is most likely over days 21–31 of August (65 % of days) and least likely over days 1–10 (56 %).
What to expect
| Measure | Typical August | Share of the month |
|---|---|---|
| Days above 25 °C | 29 of 31 | 94 % |
| Days above 30 °C | 13 of 31 | 42 % |
| Days below 0 °C | 0 of 31 | 0 % |
| Days with more than 1 mm rain | 18 of 31 | 59 % |
Conditions in August
| Measure | Average |
|---|---|
| Mean temperature | 26 °C |
| Record high (1991–2020) | 38 °C |
| Record low (1991–2020) | 16 °C |
| Relative humidity | 84 % |
| Wind speed | 10 km/h |
| Cloud cover | 67 % |
August compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| June | 24.3 °C | 164 mm | 78 % |
| July | 27.7 °C | 240 mm | 77 % |
| August | 29.2 °C | 196 mm | 67 % |
| September | 25.2 °C | 207 mm | 72 % |
| October | 19.5 °C | 188 mm | 67 % |
See all twelve months for Jōetsu
- August is the warmest month in Jōetsu.
- It is the 8th driest month of the year.
- It ranks 5th for least cloud cover.
- Days last about 14 hours from sunrise to sunset.
- It rains on 18 of 31 days — 59 % of the month.
- Nights are about 6.8 °C cooler than the middle of the day.
- The hottest August day on record since 1991 reached 38 °C, 8.5 °C above the usual daytime high.
- Beach score: 73 / 100 — see how this is calculated.
QuestionsAugust in Jōetsu, answered
How warm is Jōetsu in August?
Daily highs average 29 °C and nights fall to about 22 °C, a spread of 6.8 °C between afternoon and dawn. That makes August the 1st warmest month of the year here.
Does it rain much in Jōetsu in August?
August averages 196 mm of rain, spread over about 18 of the 31 days — 59 % of the month. Cloud cover averages 67 % of the sky.
Is the sea warm enough to swim in August?
The sea averages 27 °C off Jōetsu in August. Most people find water below 20 °C bracing and above 25 °C comfortable for a long swim; this figure is a monthly surface average, so a sheltered bay on a still afternoon can be warmer.
How long are the days in August?
Jōetsu averages 14 hours between sunrise and sunset in August. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.