Niihama, Japan climate

Cfa Humid subtropical

Niihama has a seasonal mild-temperate climate (Humid subtropical, Köppen Cfa). The hottest month is August with an average daily high near 32°C, while the coldest is January averaging around 2°C at night. Precipitation totals about 1494 mm a year and is strongly seasonal — September alone averages 230 mm while January barely receives 53 mm.

☀️ Summers

Hot

Highs near 32°C in August.

❄️ Winters

Chilly

Lows near 2°C in January.

🌧️ Rain

Wet

About 1494 mm of rain a year.

Wettest in September

⛅ Sky & trend

Often cloudy

Cloudy skies much of the year.

Temperature & precipitation

Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figures

Hours of sunshine per day

Estimated sunny hours each month — daylight length × clear-sky fraction · 1991–2020 monthly cloud cover (NASA POWER)

Niihama climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°C)	10	10	14	19	24	27	31	32	28	23	17	12
Avg temp (°C)	6	6	9	14	19	23	27	27	24	18	13	8
Avg low (°C)	2	2	5	9	14	19	23	24	20	15	9	4
Precipitation (mm)	53	69	110	103	127	209	186	125	230	152	71	59

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°C)	10	10	14	19	24	27
Avg temp (°C)	6	6	9	14	19	23
Avg low (°C)	2	2	5	9	14	19
Precipitation (mm)	53	69	110	103	127	209

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°C)	31	32	28	23	17	12
Avg temp (°C)	27	27	24	18	13	8
Avg low (°C)	23	24	20	15	9	4
Precipitation (mm)	186	125	230	152	71	59

Sky & atmosphere

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	68	69	68	66	72	83	75	66	72	65	65	65
Relative humidity (%)	81	79	77	76	78	82	83	81	81	81	80	81
Wind speed (m/s)	2.1	2.1	2.0	1.7	1.4	1.2	1.3	1.4	1.6	1.8	1.8	2.0

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Cloud cover (%)	68	69	68	66	72	83
Relative humidity (%)	81	79	77	76	78	82
Wind speed (m/s)	2.1	2.1	2.0	1.7	1.4	1.2

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	75	66	72	65	65	65
Relative humidity (%)	83	81	81	81	80	81
Wind speed (m/s)	1.3	1.4	1.6	1.8	1.8	2.0

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from the Japan Meteorological Agency, measured at Saijo, about 21 km from the city centre.

Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.

How we build these numbers →