Jōetsu weather in April
In April, Jōetsu has daytime highs averaging 15 °C, nights around 6.2 °C, with 14 wet days, and a sea temperature of 11 °C. Figures are 1991–2020 climate normals.
- 15.1°C Average high
- 6.2°C Average low
- 14days Wet days
- 116mm Rainfall
- 11.2°C Sea temperature
- 13h Daylight
Daily temperatures through April
How April 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 April | 12.7 °C | 4.0 °C | 52 % |
| 11–20 April | 15.2 °C | 6.1 °C | 44 % |
| 21–30 April | 17.3 °C | 8.2 °C | 46 % |
- Average highs rise from 12.7 °C early in April to 17.3 °C by the end of it.
- Rain is most likely over days 1–10 of April (52 % of days) and least likely over days 11–20 (44 %).
What to expect
| Measure | Typical April | Share of the month |
|---|---|---|
| Days above 25 °C | 0.2 of 30 | 1 % |
| Days above 30 °C | 0 of 30 | 0 % |
| Days below 0 °C | 1.0 of 30 | 3 % |
| Days with more than 1 mm rain | 14 of 30 | 47 % |
Conditions in April
| Measure | Average |
|---|---|
| Mean temperature | 10 °C |
| Record high (1991–2020) | 26 °C |
| Record low (1991–2020) | -3.5 °C |
| Relative humidity | 77 % |
| Wind speed | 14 km/h |
| Cloud cover | 63 % |
April compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| February | 4.7 °C | 185 mm | 72 % |
| March | 8.3 °C | 162 mm | 68 % |
| April | 15.1 °C | 116 mm | 63 % |
| May | 21.0 °C | 126 mm | 66 % |
| June | 24.3 °C | 164 mm | 78 % |
See all twelve months for Jōetsu
- April is the 7th warmest month here.
- It is the 1st driest month of the year.
- It ranks 1st for least cloud cover.
- Days last about 13 hours from sunrise to sunset.
- It rains on 14 of 30 days — 47 % of the month.
- Nights are about 9.0 °C cooler than the middle of the day.
- The hottest April day on record since 1991 reached 26 °C, 11 °C above the usual daytime high.
- Beach score: 6 / 100 — see how this is calculated.
QuestionsApril in Jōetsu, answered
How warm is Jōetsu in April?
Daily highs average 15 °C and nights fall to about 6.2 °C, a spread of 9.0 °C between afternoon and dawn. That makes April the 7th warmest month of the year here.
Does it rain much in Jōetsu in April?
April averages 116 mm of rain, spread over about 14 of the 30 days — 47 % of the month. Cloud cover averages 63 % of the sky.
Is the sea warm enough to swim in April?
The sea averages 11 °C off Jōetsu in April. 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 April?
Jōetsu averages 13 hours between sunrise and sunset in April. 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.