Nagasaki climate

Name: Nagasaki
Address: JP

Nagasaki is warmest in August, with average highs of 29 °C, and coldest in January, when nights average 6.1 °C. June is the wettest month (446 mm) and January the driest (80 mm). Figures are 1991–2020 climate normals.

Across a full year Nagasaki averages 2,168 mm of rain, 98 days above 25 °C and 1 days below freezing.

Japan · population 409,118 · 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 January 6.1 °C
Driest month January 80 mm
Wettest month June 446 mm
Least cloud October 46 % cloud
Hottest on record August 37 °C
Coldest on record January -1.4 °C
Warmest sea August 28 °C

What to expectNagasaki through the year

Nagasaki has a clear annual cycle: average daily highs run from 9.7 °C in January to 29 °C in August, a swing of 19 °C in mean temperature across the year.

Counted across a normal year, 98 days a year reach 25 °C, 15 of them reach 30 °C, 1 nights drop below freezing. The warmest reading in the 1991–2020 record is 37 °C, in August.

Rain is strongly seasonal. June averages 446 mm against 80 mm in January — 5.6 times as much. Planning around the dry months matters more here than planning around temperature.

The sea off Nagasaki is warmest in August at 28 °C and coldest in February at 16 °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	9.7 °C	80 mm	68 %
February	10.6 °C	99 mm	64 %
March	13.5 °C	149 mm	62 %
April	17.5 °C	169 mm	62 %
May	21.4 °C	191 mm	66 %
June	24.3 °C	446 mm	79 %
July	27.6 °C	342 mm	69 %
August	29.3 °C	184 mm	59 %
September	26.8 °C	208 mm	55 %
October	22.3 °C	107 mm	46 %
November	17.1 °C	105 mm	52 %
December	11.9 °C	90 mm	61 %

Temperature month by month

Month	Avg high	Avg low	Mean	Record high	Record low	Days above 25 °C	Days above 30 °C
January	9.7 °C	6.1 °C	7.9 °C	18.6 °C	-1.4 °C	0	0
February	10.6 °C	6.3 °C	8.5 °C	19.2 °C	-0.9 °C	0	0
March	13.5 °C	8.8 °C	11.1 °C	22.5 °C	1.6 °C	0	0
April	17.5 °C	12.8 °C	15.0 °C	24.8 °C	5.6 °C	0	0
May	21.4 °C	16.8 °C	18.9 °C	27.6 °C	10.5 °C	1	0
June	24.3 °C	20.5 °C	22.2 °C	31.5 °C	15.7 °C	10	0
July	27.6 °C	24.4 °C	25.8 °C	36.0 °C	18.2 °C	28	3
August	29.3 °C	25.5 °C	27.2 °C	36.8 °C	19.6 °C	31	10
September	26.8 °C	22.6 °C	24.4 °C	31.9 °C	17.3 °C	23	2
October	22.3 °C	18.1 °C	20.0 °C	29.5 °C	9.7 °C	4	0
November	17.1 °C	13.2 °C	15.1 °C	24.1 °C	4.4 °C	0	0
December	11.9 °C	8.3 °C	10.1 °C	22.6 °C	-0.1 °C	0	0

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind	Sea temp
January	80 mm	10	10 h/day	68 %	67 %	24 km/h	16.7 °C
February	99 mm	10	11 h/day	64 %	68 %	24 km/h	15.6 °C
March	149 mm	12	12 h/day	62 %	70 %	24 km/h	16.0 °C
April	169 mm	11	13 h/day	62 %	75 %	22 km/h	17.4 °C
May	191 mm	11	14 h/day	66 %	80 %	19 km/h	19.6 °C
June	446 mm	17	14 h/day	79 %	87 %	19 km/h	22.3 °C
July	342 mm	17	14 h/day	69 %	89 %	20 km/h	25.4 °C
August	184 mm	14	13 h/day	59 %	84 %	19 km/h	27.6 °C
September	208 mm	12	12 h/day	55 %	79 %	20 km/h	26.6 °C
October	107 mm	7	11 h/day	46 %	71 %	21 km/h	24.1 °C
November	105 mm	9	10 h/day	52 %	69 %	21 km/h	21.4 °C
December	90 mm	11	10 h/day	61 %	67 %	24 km/h	18.7 °C

How Nagasaki 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
Nagasaki	29 °C	6.1 °C	2,168 mm	98
Sasebo · Japan	30 °C	4.9 °C	1,810 mm	108
Saga · Japan	30 °C	3.0 °C	1,882 mm	115
Kumamoto · Japan	30 °C	3.0 °C	1,953 mm	118

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

QuestionsCommon questions about Nagasaki’s climate

When is the best time to visit Nagasaki?

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 Nagasaki get?

In August, the warmest month, daily highs average 29 °C. About 15 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 6.1 °C in January, the coldest month. A normal year has 1 nights below freezing.

Which month is wettest in Nagasaki?

June, averaging 446 mm over 17 days with rain. The driest month is January with 80 mm. The year as a whole averages 2,168 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 Nagasaki 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.