Sasebo climate

Name: Sasebo
Address: JP

Sasebo is warmest in August, with average highs of 30 °C, and coldest in January, when nights average 4.9 °C. June is the wettest month (319 mm) and January the driest (63 mm). Figures are 1991–2020 climate normals.

Across a full year Sasebo averages 1,810 mm of rain, 108 days above 25 °C and 2 days below freezing.

Japan · population 243,223 · 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 4.9 °C
Driest month January 63 mm
Wettest month June 319 mm
Least cloud October 48 % cloud
Hottest on record August 37 °C
Coldest on record January -2.9 °C
Warmest sea August 27 °C

What to expectSasebo through the year

Sasebo has a clear annual cycle: average daily highs run from 9.2 °C in January to 30 °C in August, a swing of 20 °C in mean temperature across the year.

Counted across a normal year, 108 days a year reach 25 °C, 29 of them reach 30 °C, 2 nights drop below freezing. The warmest reading in the 1991–2020 record is 37 °C, in August.

Rain is strongly seasonal. June averages 319 mm against 63 mm in January — 5.0 times as much. Planning around the dry months matters more here than planning around temperature.

The sea off Sasebo is warmest in August at 27 °C and coldest in February at 15 °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	9.2 °C	63 mm	69 %
February	10.3 °C	77 mm	65 %
March	13.6 °C	120 mm	63 %
April	18.2 °C	143 mm	62 %
May	22.4 °C	149 mm	66 %
June	25.3 °C	319 mm	79 %
July	28.6 °C	290 mm	71 %
August	30.1 °C	185 mm	61 %
September	27.0 °C	201 mm	57 %
October	22.3 °C	103 mm	48 %
November	16.9 °C	91 mm	53 %
December	11.5 °C	69 mm	61 %

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	9.2 °C	4.9 °C	6.9 °C	18.2 °C	-2.9 °C	0	0	1
February	10.3 °C	5.2 °C	7.6 °C	19.6 °C	-1.9 °C	0	0	1
March	13.6 °C	7.8 °C	10.4 °C	22.2 °C	-1.3 °C	0	0	0
April	18.2 °C	11.8 °C	14.7 °C	26.5 °C	2.9 °C	0	0	0
May	22.4 °C	16.0 °C	18.9 °C	29.7 °C	9.2 °C	4	0	0
June	25.3 °C	20.0 °C	22.3 °C	33.0 °C	14.9 °C	17	0	0
July	28.6 °C	24.1 °C	26.0 °C	35.7 °C	17.6 °C	29	9	0
August	30.1 °C	25.1 °C	27.2 °C	36.6 °C	18.4 °C	31	16	0
September	27.0 °C	21.8 °C	24.0 °C	33.6 °C	14.5 °C	23	3	0
October	22.3 °C	17.0 °C	19.2 °C	29.9 °C	9.0 °C	5	0	0
November	16.9 °C	11.9 °C	14.1 °C	24.9 °C	2.4 °C	0	0	0
December	11.5 °C	7.0 °C	9.1 °C	21.9 °C	-1.5 °C	0	0	0

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind	Sea temp
January	63 mm	8	10 h/day	69 %	68 %	19 km/h	16.0 °C
February	77 mm	8	11 h/day	65 %	69 %	19 km/h	14.7 °C
March	120 mm	11	12 h/day	63 %	71 %	19 km/h	15.1 °C
April	143 mm	10	13 h/day	62 %	74 %	18 km/h	16.3 °C
May	149 mm	10	14 h/day	66 %	78 %	16 km/h	18.6 °C
June	319 mm	16	14 h/day	79 %	85 %	16 km/h	21.4 °C
July	290 mm	16	14 h/day	71 %	87 %	17 km/h	24.7 °C
August	185 mm	15	13 h/day	61 %	83 %	16 km/h	27.0 °C
September	201 mm	13	12 h/day	57 %	80 %	17 km/h	25.8 °C
October	103 mm	7	11 h/day	48 %	72 %	17 km/h	23.5 °C
November	91 mm	7	10 h/day	53 %	71 %	17 km/h	20.9 °C
December	69 mm	7	10.0 h/day	61 %	68 %	18 km/h	18.2 °C

How Sasebo 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
Sasebo	30 °C	4.9 °C	1,810 mm	108
Nagasaki · Japan	29 °C	6.1 °C	2,168 mm	98
Saga · Japan	30 °C	3.0 °C	1,882 mm	115
Kurume · Japan	31 °C	1.8 °C	1,917 mm	122
Fukuoka · Japan	31 °C	3.3 °C	1,725 mm	111

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

QuestionsCommon questions about Sasebo’s climate

When is the best time to visit Sasebo?

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

How hot does Sasebo get?

In August, the warmest month, daily highs average 30 °C. About 29 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 4.9 °C in January, the coldest month. A normal year has 2 nights below freezing.

Which month is wettest in Sasebo?

June, averaging 319 mm over 16 days with rain. The driest month is January with 63 mm. The year as a whole averages 1,810 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 Sasebo 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: 33.168°, 129.725° (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.