Jōetsu climate

Name: Jōetsu
Address: JP

Jōetsu is warmest in August, with average highs of 29 °C, and coldest in February, when nights average -0.6 °C. January is the wettest month (248 mm) and April the driest (116 mm). Figures are 1991–2020 climate normals.

Across a full year Jōetsu averages 2,259 mm of rain, 86 days above 25 °C and 57 days below freezing.

Japan · population 189,430 · 1991–2020 normals

Temperature below 0 °C to above 30 °C Rain band height is that month’s share of the wettest month

Warmest month August 29 °C
Coldest month February -0.6 °C
Driest month April 116 mm
Wettest month January 248 mm
Least cloud April 63 % cloud
Hottest on record August 38 °C
Coldest on record January -8.1 °C
Warmest sea August 27 °C

What to expectJōetsu through the year

Jōetsu has a clear annual cycle: average daily highs run from 4.7 °C in February to 29 °C in August, a swing of 24 °C in mean temperature across the year.

Counted across a normal year, 86 days a year reach 25 °C, 23 of them reach 30 °C, 57 nights drop below freezing. The warmest reading in the 1991–2020 record is 38 °C, in August.

Rain is strongly seasonal. January averages 248 mm against 116 mm in April — 2.1 times as much. Planning around the dry months matters more here than planning around temperature.

The sea off Jōetsu is warmest in August at 27 °C and coldest in March at 10 °C. Sea temperature lags the air by a month or two, which is why late summer swims warmer than early summer at the same air temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	4.2 °C	248 mm	74 %
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 %
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 %
November	13.7 °C	183 mm	66 %
December	7.5 °C	245 mm	70 %

Temperature month by month

Month	Avg high	Avg low	Mean	Record high	Record low	Days above 25 °C	Days above 30 °C	Days below 0 °C
January	4.2 °C	-0.6 °C	1.7 °C	14.3 °C	-8.1 °C	0	0	19
February	4.7 °C	-0.6 °C	1.8 °C	18.4 °C	-7.7 °C	0	0	18
March	8.3 °C	1.3 °C	4.5 °C	22.3 °C	-6.6 °C	0	0	10
April	15.1 °C	6.2 °C	10.3 °C	26.2 °C	-3.5 °C	0	0	1
May	21.0 °C	12.1 °C	16.3 °C	29.5 °C	2.5 °C	3	0	0
June	24.3 °C	16.8 °C	20.4 °C	32.2 °C	8.5 °C	12	1	0
July	27.7 °C	21.3 °C	24.3 °C	35.7 °C	14.2 °C	26	7	0
August	29.2 °C	22.4 °C	25.6 °C	37.7 °C	15.5 °C	29	13	0
September	25.2 °C	18.7 °C	21.6 °C	36.8 °C	9.6 °C	14	3	0
October	19.5 °C	12.8 °C	15.8 °C	31.6 °C	3.8 °C	1	0	0
November	13.7 °C	7.0 °C	9.9 °C	23.5 °C	-5.2 °C	0	0	0
December	7.5 °C	1.7 °C	4.3 °C	22.3 °C	-7.8 °C	0	0	9

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind	Sea temp
January	248 mm	26	9.9 h/day	74 %	82 %	15 km/h	12.7 °C
February	185 mm	21	11 h/day	72 %	81 %	15 km/h	10.8 °C
March	162 mm	19	12 h/day	68 %	79 %	14 km/h	10.1 °C
April	116 mm	14	13 h/day	63 %	77 %	14 km/h	11.2 °C
May	126 mm	14	14 h/day	66 %	78 %	12 km/h	14.9 °C
June	164 mm	17	15 h/day	78 %	83 %	11 km/h	19.6 °C
July	240 mm	20	14 h/day	77 %	87 %	9.9 km/h	23.4 °C
August	196 mm	18	14 h/day	67 %	84 %	10 km/h	26.6 °C
September	207 mm	17	12 h/day	72 %	84 %	11 km/h	25.3 °C
October	188 mm	16	11 h/day	67 %	82 %	12 km/h	21.8 °C
November	183 mm	19	10 h/day	66 %	82 %	13 km/h	18.5 °C
December	245 mm	23	9.6 h/day	70 %	83 %	15 km/h	15.4 °C

How Jōetsu compares

The same four figures for nearby destinations, so the numbers above have something to be read against. Summer high is the warmest month's average high; winter low is the coldest month's average low.

Destination	Summer high	Winter low	Rain per year	Days above 25 °C
Jōetsu	29 °C	-0.6 °C	2,259 mm	86
Nagano · Japan	28 °C	-4.4 °C	1,778 mm	77
Nagaoka · Japan	30 °C	-2.7 °C	1,747 mm	96
Ueda · Japan	29 °C	-4.5 °C	1,513 mm	81
Toyama · Japan	29 °C	-2.6 °C	2,254 mm	79
Matsumoto · Japan	28 °C	-5.9 °C	1,831 mm	80

Planning a trip? See the best time to visit Jōetsu.

QuestionsCommon questions about Jōetsu’s climate

When is the best time to visit Jōetsu?

That depends on what you want, so the honest answer is a comparison rather than a single month. May, June, September sit closest to 20 °C on average, August is the warmest month and April the driest. The month-by-month table above has the full picture.

How hot does Jōetsu get?

In August, the warmest month, daily highs average 29 °C. About 23 days a year pass 30 °C. The highest value in the 1991–2020 record is 38 °C.

How cold does it get in winter?

Nights average -0.6 °C in February, the coldest month. A normal year has 57 nights below freezing.

Which month is wettest in Jōetsu?

January, averaging 248 mm over 26 days with rain. The driest month is April with 116 mm. The year as a whole averages 2,259 mm.

Are these figures a forecast?

No. They are 1991–2020 climate normals: the average of thirty years, which describes what a month is usually like in Jōetsu rather than what any particular week will bring. Individual years can differ substantially from the normal.

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: 1 August 2026

Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: monthly rankings, daylight hours, beach and comfort scores. 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.