Oyama climate

Name: Oyama
Address: JP

Oyama is warmest in August, with average highs of 30 °C, and coldest in January, when nights average -1.8 °C. September is the wettest month (210 mm) and December the driest (52 mm). Figures are 1991–2020 climate normals.

Across a full year Oyama averages 1,576 mm of rain, 96 days above 25 °C and 69 days below freezing.

Japan · population 167,647 · 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 30 °C
Coldest month January -1.8 °C
Driest month December 52 mm
Wettest month September 210 mm
Least cloud January 37 % cloud
Hottest on record July 37 °C
Coldest on record January -14 °C

What to expectOyama through the year

Oyama has a clear annual cycle: average daily highs run from 7.4 °C in January to 30 °C in August, a swing of 23 °C in mean temperature across the year.

Counted across a normal year, 96 days a year reach 25 °C, 31 of them reach 30 °C, 69 nights drop below freezing. The warmest reading in the 1991–2020 record is 37 °C, in July.

Rain is strongly seasonal. September averages 210 mm against 52 mm in December — 4.0 times as much. Planning around the dry months matters more here than planning around temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	7.4 °C	56 mm	37 %
February	8.5 °C	56 mm	45 %
March	12.3 °C	102 mm	55 %
April	17.6 °C	118 mm	60 %
May	22.2 °C	156 mm	69 %
June	24.9 °C	180 mm	81 %
July	28.4 °C	203 mm	78 %
August	29.7 °C	159 mm	70 %
September	25.9 °C	210 mm	71 %
October	20.4 °C	200 mm	62 %
November	15.0 °C	84 mm	50 %
December	9.8 °C	52 mm	38 %

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	7.4 °C	-1.8 °C	2.2 °C	16.6 °C	-13.8 °C	0	0	25
February	8.5 °C	-0.9 °C	3.3 °C	20.5 °C	-9.6 °C	0	0	19
March	12.3 °C	2.3 °C	6.9 °C	24.5 °C	-4.9 °C	0	0	9
April	17.6 °C	7.6 °C	12.3 °C	28.4 °C	-2.4 °C	1	0	1
May	22.2 °C	12.9 °C	17.2 °C	32.0 °C	2.9 °C	6	0	0
June	24.9 °C	17.4 °C	20.8 °C	33.4 °C	9.8 °C	15	2	0
July	28.4 °C	21.3 °C	24.4 °C	37.2 °C	14.3 °C	26	11	0
August	29.7 °C	22.5 °C	25.6 °C	36.6 °C	16.2 °C	28	15	0
September	25.9 °C	19.0 °C	22.0 °C	34.9 °C	9.2 °C	18	3	0
October	20.4 °C	12.9 °C	16.3 °C	31.1 °C	3.1 °C	2	0	0
November	15.0 °C	6.3 °C	10.3 °C	23.0 °C	-3.3 °C	0	0	1
December	9.8 °C	0.6 °C	4.7 °C	22.7 °C	-7.8 °C	0	0	15

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind
January	56 mm	6	10.0 h/day	37 %	69 %	16 km/h
February	56 mm	7	11 h/day	45 %	68 %	17 km/h
March	102 mm	12	12 h/day	55 %	70 %	17 km/h
April	118 mm	12	13 h/day	60 %	73 %	18 km/h
May	156 mm	13	14 h/day	69 %	76 %	16 km/h
June	180 mm	17	15 h/day	81 %	81 %	14 km/h
July	203 mm	18	14 h/day	78 %	84 %	13 km/h
August	159 mm	15	14 h/day	70 %	82 %	13 km/h
September	210 mm	15	12 h/day	71 %	82 %	14 km/h
October	200 mm	13	11 h/day	62 %	80 %	13 km/h
November	84 mm	8	10 h/day	50 %	78 %	12 km/h
December	52 mm	6	9.7 h/day	38 %	73 %	14 km/h

How Oyama 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
Oyama	30 °C	-1.8 °C	1,576 mm	96
Tochigi · Japan	29 °C	-1.9 °C	1,777 mm	93
Utsunomiya · Japan	28 °C	-2.5 °C	1,399 mm	80
Tsukuba · Japan	30 °C	-0.9 °C	1,412 mm	96

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

QuestionsCommon questions about Oyama’s climate

When is the best time to visit Oyama?

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 December the driest. The month-by-month table above has the full picture.

How hot does Oyama get?

In August, the warmest month, daily highs average 30 °C. About 31 days a year pass 30 °C. The highest value in the 1991–2020 record is 37 °C.

How cold does it get in winter?

Nights average -1.8 °C in January, the coldest month. A normal year has 69 nights below freezing.

Which month is wettest in Oyama?

September, averaging 210 mm over 15 days with rain. The driest month is December with 52 mm. The year as a whole averages 1,576 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 Oyama 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
Data point: 36.300°, 139.800° (the coordinates the reanalysis values are taken for)
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.