Niiza climate

Name: Niiza
Address: JP

Niiza is warmest in August, with average highs of 30 °C, and coldest in January, when nights average -1.3 °C. October is the wettest month (215 mm) and December the driest (60 mm). Figures are 1991–2020 climate normals.

Across a full year Niiza averages 1,599 mm of rain, 97 days above 25 °C and 54 days below freezing.

Japan · population 166,017 · 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 -1.3 °C
Driest month December 60 mm
Wettest month October 215 mm
Least cloud January 39 % cloud
Hottest on record July 40 °C
Coldest on record February -15 °C

What to expectNiiza through the year

Niiza has a clear annual cycle: average daily highs run from 7.9 °C in January to 30 °C in August, a swing of 23 °C in mean temperature across the year.

Counted across a normal year, 97 days a year reach 25 °C, 32 of them reach 30 °C, 54 nights drop below freezing. The warmest reading in the 1991–2020 record is 40 °C, in July.

Rain is strongly seasonal. October averages 215 mm against 60 mm in December — 3.6 times as much. Planning around the dry months matters more here than planning around temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	7.9 °C	70 mm	39 %
February	8.9 °C	69 mm	48 %
March	12.4 °C	116 mm	58 %
April	17.6 °C	122 mm	62 %
May	22.2 °C	141 mm	69 %
June	24.9 °C	181 mm	81 %
July	28.6 °C	179 mm	76 %
August	30.0 °C	144 mm	67 %
September	26.1 °C	211 mm	69 %
October	20.6 °C	215 mm	63 %
November	15.4 °C	89 mm	52 %
December	10.4 °C	60 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	7.9 °C	-1.3 °C	2.9 °C	17.5 °C	-13.8 °C	0	0	21
February	8.9 °C	-0.4 °C	3.8 °C	21.2 °C	-15.3 °C	0	0	16
March	12.4 °C	3.2 °C	7.5 °C	24.3 °C	-5.3 °C	0	0	6
April	17.6 °C	8.6 °C	12.8 °C	28.0 °C	-1.3 °C	0	0	0
May	22.2 °C	13.8 °C	17.7 °C	30.5 °C	4.2 °C	5	0	0
June	24.9 °C	18.1 °C	21.2 °C	32.6 °C	10.6 °C	15	1	0
July	28.6 °C	22.1 °C	25.0 °C	39.9 °C	15.2 °C	26	11	0
August	30.0 °C	23.2 °C	26.2 °C	37.1 °C	16.3 °C	29	16	0
September	26.1 °C	19.7 °C	22.5 °C	35.8 °C	9.7 °C	19	3	0
October	20.6 °C	13.7 °C	16.8 °C	30.2 °C	4.2 °C	2	0	0
November	15.4 °C	7.4 °C	11.0 °C	24.2 °C	-4.4 °C	0	0	0
December	10.4 °C	1.6 °C	5.6 °C	23.0 °C	-9.3 °C	0	0	10

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind
January	70 mm	7	10 h/day	39 %	70 %	16 km/h
February	69 mm	9	11 h/day	48 %	69 %	18 km/h
March	116 mm	13	12 h/day	58 %	71 %	20 km/h
April	122 mm	13	13 h/day	62 %	73 %	21 km/h
May	141 mm	12	14 h/day	69 %	76 %	19 km/h
June	181 mm	16	15 h/day	81 %	81 %	16 km/h
July	179 mm	16	14 h/day	76 %	83 %	16 km/h
August	144 mm	14	14 h/day	67 %	81 %	16 km/h
September	211 mm	14	12 h/day	69 %	81 %	16 km/h
October	215 mm	13	11 h/day	63 %	80 %	15 km/h
November	89 mm	9	10 h/day	52 %	77 %	14 km/h
December	60 mm	7	9.7 h/day	41 %	72 %	15 km/h

How Niiza 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
Niiza	30 °C	-1.3 °C	1,599 mm	97
Tokorozawa · Japan	29 °C	-2.0 °C	1,616 mm	88
Kawagoe · Japan	30 °C	-2.0 °C	1,432 mm	95
Saitama · Japan	30 °C	-1.4 °C	1,396 mm	100
Kawaguchi · Japan	30 °C	-1.0 °C	1,458 mm	100
Tokyo · Japan	30 °C	-0.3 °C	1,465 mm	93

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

QuestionsCommon questions about Niiza’s climate

When is the best time to visit Niiza?

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 Niiza get?

In August, the warmest month, daily highs average 30 °C. About 32 days a year pass 30 °C. The highest value in the 1991–2020 record is 40 °C.

How cold does it get in winter?

Nights average -1.3 °C in January, the coldest month. A normal year has 54 nights below freezing.

Which month is wettest in Niiza?

October, averaging 215 mm over 13 days with rain. The driest month is December with 60 mm. The year as a whole averages 1,599 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 Niiza 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.