Tomakomai climate

Name: Tomakomai
Address: JP

Tomakomai is warmest in August, with average highs of 23 °C, and coldest in January, when nights average -7.6 °C. August is the wettest month (196 mm) and February the driest (45 mm). Figures are 1991–2020 climate normals.

Across a full year Tomakomai averages 1,215 mm of rain, 7 days above 25 °C and 130 days below freezing.

Japan · population 174,806 · 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 23 °C
Coldest month January -7.6 °C
Driest month February 45 mm
Wettest month August 196 mm
Least cloud October 55 % cloud
Hottest on record August 30 °C
Coldest on record January -19 °C
Warmest sea August 20 °C

What to expectTomakomai through the year

Tomakomai has a clear annual cycle: average daily highs run from -1.9 °C in January to 23 °C in August, a swing of 25 °C in mean temperature across the year.

Counted across a normal year, 7 days a year reach 25 °C, 0 of them reach 30 °C, 130 nights drop below freezing. The warmest reading in the 1991–2020 record is 30 °C, in August.

Rain is strongly seasonal. August averages 196 mm against 45 mm in February — 4.4 times as much. Planning around the dry months matters more here than planning around temperature.

The sea off Tomakomai is warmest in August at 20 °C and coldest in March at 3.2 °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	-1.9 °C	45 mm	59 %
February	-1.3 °C	45 mm	58 %
March	2.4 °C	63 mm	58 %
April	7.8 °C	78 mm	59 %
May	13.0 °C	111 mm	66 %
June	16.9 °C	103 mm	72 %
July	20.7 °C	139 mm	77 %
August	22.6 °C	196 mm	74 %
September	20.2 °C	179 mm	66 %
October	14.4 °C	114 mm	55 %
November	7.3 °C	79 mm	55 %
December	0.8 °C	63 mm	60 %

Temperature month by month

Month	Avg high	Avg low	Mean	Record high	Record low	Days above 25 °C	Days below 0 °C
January	-1.9 °C	-7.6 °C	-4.5 °C	7.3 °C	-18.6 °C	0	31
February	-1.3 °C	-7.3 °C	-4.1 °C	7.7 °C	-18.2 °C	0	28
March	2.4 °C	-3.5 °C	-0.6 °C	13.4 °C	-13.1 °C	0	26
April	7.8 °C	1.5 °C	4.5 °C	19.0 °C	-9.4 °C	0	9
May	13.0 °C	7.0 °C	9.9 °C	26.1 °C	-0.7 °C	0	0
June	16.9 °C	11.9 °C	14.2 °C	26.2 °C	5.2 °C	0	0
July	20.7 °C	16.4 °C	18.4 °C	29.8 °C	9.2 °C	1	0
August	22.6 °C	18.4 °C	20.3 °C	30.3 °C	10.9 °C	5	0
September	20.2 °C	15.2 °C	17.6 °C	27.5 °C	6.3 °C	1	0
October	14.4 °C	9.0 °C	11.6 °C	22.8 °C	0.3 °C	0	0
November	7.3 °C	2.0 °C	4.6 °C	17.1 °C	-10.1 °C	0	8
December	0.8 °C	-4.3 °C	-1.7 °C	11.8 °C	-14.0 °C	0	28

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind	Sea temp
January	45 mm	8	9.4 h/day	59 %	74 %	19 km/h	6.2 °C
February	45 mm	7	11 h/day	58 %	74 %	19 km/h	3.5 °C
March	63 mm	10	12 h/day	58 %	76 %	20 km/h	3.2 °C
April	78 mm	10	13 h/day	59 %	78 %	18 km/h	4.9 °C
May	111 mm	13	15 h/day	66 %	81 %	17 km/h	8.1 °C
June	103 mm	12	15 h/day	72 %	87 %	15 km/h	12.8 °C
July	139 mm	14	15 h/day	77 %	89 %	14 km/h	17.0 °C
August	196 mm	15	14 h/day	74 %	88 %	15 km/h	20.0 °C
September	179 mm	14	13 h/day	66 %	82 %	17 km/h	19.6 °C
October	114 mm	12	11 h/day	55 %	75 %	20 km/h	16.3 °C
November	79 mm	10	9.8 h/day	55 %	73 %	20 km/h	12.7 °C
December	63 mm	8	9.1 h/day	60 %	73 %	20 km/h	9.5 °C

How Tomakomai 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
Tomakomai	23 °C	-7.6 °C	1,215 mm	7
Sapporo · Japan	24 °C	-9.4 °C	1,162 mm	25
Hakodate · Japan	24 °C	-5.4 °C	1,176 mm	17
Obihiro · Japan	24 °C	-14 °C	1,158 mm	30
Asahikawa · Japan	24 °C	-12 °C	1,212 mm	30
Aomori · Japan	27 °C	-5.7 °C	1,300 mm	54
Kushiro · Japan	20 °C	-8.8 °C	1,133 mm	1

Where Tomakomai ranks

Ranking	Position	Value
The coolest places in Asia in June	3rd of 50	17 °C
The coolest places in Asia in April	4th of 50	7.8 °C
The coolest places in Asia in May	4th of 50	13 °C
The coolest places in Asia in July	8th of 50	21 °C
The coolest places in Asia in August	19th of 50	23 °C
The coolest places in Asia in March	29th of 50	2.4 °C

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

QuestionsCommon questions about Tomakomai’s climate

When is the best time to visit Tomakomai?

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

How hot does Tomakomai get?

In August, the warmest month, daily highs average 23 °C. About 0 days a year pass 30 °C. The highest value in the 1991–2020 record is 30 °C.

How cold does it get in winter?

Nights average -7.6 °C in January, the coldest month. A normal year has 130 nights below freezing.

Which month is wettest in Tomakomai?

August, averaging 196 mm over 15 days with rain. The driest month is February with 45 mm. The year as a whole averages 1,215 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 Tomakomai 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: 42.637°, 141.603° (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.