Hachiōji climate

Name: Hachiōji
Address: JP

Hachiōji is warmest in August, with average highs of 29 °C, and coldest in January, when nights average -1.9 °C. September is the wettest month (250 mm) and December the driest (67 mm). Figures are 1991–2020 climate normals.

Across a full year Hachiōji averages 1,901 mm of rain, 85 days above 25 °C and 64 days below freezing.

Japan · population 579,355 · 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 -1.9 °C
Driest month December 67 mm
Wettest month September 250 mm
Least cloud January 39 % cloud
Hottest on record July 38 °C
Coldest on record February -16 °C

What to expectHachiōji through the year

Hachiōji has a clear annual cycle: average daily highs run from 7.8 °C in January to 29 °C in August, a swing of 23 °C in mean temperature across the year.

Counted across a normal year, 85 days a year reach 25 °C, 22 of them reach 30 °C, 64 nights drop below freezing. The warmest reading in the 1991–2020 record is 38 °C, in July.

Rain is strongly seasonal. September averages 250 mm against 67 mm in December — 3.8 times as much. Planning around the dry months matters more here than planning around temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	7.8 °C	77 mm	39 %
February	8.6 °C	78 mm	49 %
March	12.0 °C	134 mm	59 %
April	17.1 °C	144 mm	63 %
May	21.4 °C	165 mm	71 %
June	24.1 °C	223 mm	83 %
July	27.7 °C	232 mm	78 %
August	28.8 °C	199 mm	69 %
September	25.2 °C	250 mm	71 %
October	19.9 °C	236 mm	65 %
November	15.1 °C	98 mm	52 %
December	10.3 °C	67 mm	41 %

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	7.8 °C	-1.9 °C	2.4 °C	17.3 °C	-16.0 °C	0	0	24
February	8.6 °C	-1.1 °C	3.3 °C	21.6 °C	-16.5 °C	0	0	18
March	12.0 °C	2.4 °C	6.9 °C	23.9 °C	-11.7 °C	0	0	8
April	17.1 °C	7.6 °C	12.2 °C	28.4 °C	-4.1 °C	0	0	1
May	21.4 °C	12.7 °C	16.9 °C	30.3 °C	3.3 °C	4	0	0
June	24.1 °C	17.2 °C	20.4 °C	32.6 °C	9.6 °C	11	1	0
July	27.7 °C	21.2 °C	24.2 °C	37.8 °C	14.6 °C	24	8	0
August	28.8 °C	22.2 °C	25.2 °C	35.5 °C	15.0 °C	28	11	0
September	25.2 °C	18.8 °C	21.7 °C	35.9 °C	8.2 °C	16	2	0
October	19.9 °C	12.9 °C	16.2 °C	29.7 °C	3.3 °C	2	0	0
November	15.1 °C	6.8 °C	10.5 °C	23.9 °C	-7.0 °C	0	0	0
December	10.3 °C	1.0 °C	5.2 °C	22.9 °C	-16.1 °C	0	0	13

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind
January	77 mm	8	10 h/day	39 %	71 %	12 km/h
February	78 mm	10	11 h/day	49 %	70 %	13 km/h
March	134 mm	15	12 h/day	59 %	73 %	14 km/h
April	144 mm	14	13 h/day	63 %	76 %	15 km/h
May	165 mm	15	14 h/day	71 %	79 %	14 km/h
June	223 mm	20	15 h/day	83 %	85 %	12 km/h
July	232 mm	21	14 h/day	78 %	87 %	11 km/h
August	199 mm	19	14 h/day	69 %	85 %	11 km/h
September	250 mm	18	12 h/day	71 %	84 %	12 km/h
October	236 mm	15	11 h/day	65 %	82 %	11 km/h
November	98 mm	10	10 h/day	52 %	79 %	11 km/h
December	67 mm	8	9.8 h/day	41 %	74 %	11 km/h

How Hachiōji 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
Hachiōji	29 °C	-1.9 °C	1,901 mm	85
Aihara · Japan	28 °C	-1.5 °C	1,881 mm	80
Machida · Japan	28 °C	0.4 °C	1,619 mm	75
Tokorozawa · Japan	29 °C	-2.0 °C	1,616 mm	88
Atsugi · Japan	28 °C	1.8 °C	1,863 mm	74

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

QuestionsCommon questions about Hachiōji’s climate

When is the best time to visit Hachiōji?

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 Hachiōji get?

In August, the warmest month, daily highs average 29 °C. About 22 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 -1.9 °C in January, the coldest month. A normal year has 64 nights below freezing.

Which month is wettest in Hachiōji?

September, averaging 250 mm over 18 days with rain. The driest month is December with 67 mm. The year as a whole averages 1,901 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 Hachiōji 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.