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Monthly climate in Iwaki, Japan

Last updated: July 31, 2025

Under the Köppen–Geiger climate classification Iwaki features a humid subtropical climate (Cfa). Temperatures typically range between 5 °C (42 °F) and 25 °C (76 °F) through the year, but rarely can drop to -4 °C (26 °F) or can rise to as high as 30 °C (87 °F). The average annual precipitation amounts to about 1652 mm (65.0 inches) and receives 138 rainy days on the 1 mm (0.04 inches) threshold annually. Iwaki enjoys an average of 2997 hours of sunshine throughout the year, and daylight varies from 9 hours 39 minutes to 14 hours 38 minutes per day.

Monthly average temperatures in Iwaki, Japan

The warmest months in Iwaki are July, August and September, with daily mean temperatures ranging from 22 to 25 °C (72 - 76 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 5 to 8 °C (42 - 46 °F) throughout the day. On average each year, Iwaki experiences 30 days above 25 °C (77.0 °F) and 3 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Iwaki. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to June 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Maximum14°C
(58°F)		17°C
(63°F)		18°C
(64°F)		21°C
(70°F)		23°C
(74°F)		26°C
(78°F)		30°C
(86°F)		30°C
(87°F)		29°C
(84°F)		26°C
(78°F)		20°C
(68°F)		18°C
(65°F)
Mean maximum12°C
(55°F)		14°C
(57°F)		16°C
(60°F)		19°C
(66°F)		22°C
(72°F)		23°C
(74°F)		27°C
(80°F)		29°C
(84°F)		27°C
(81°F)		24°C
(76°F)		19°C
(67°F)		16°C
(61°F)
Average high7°C
(46°F)		8°C
(47°F)		11°C
(52°F)		14°C
(57°F)		18°C
(65°F)		20°C
(69°F)		23°C
(75°F)		26°C
(79°F)		23°C
(74°F)		19°C
(67°F)		15°C
(59°F)		10°C
(50°F)
Daily mean5°C
(42°F)		6°C
(42°F)		8°C
(47°F)		11°C
(53°F)		16°C
(61°F)		19°C
(66°F)		22°C
(72°F)		25°C
(76°F)		22°C
(72°F)		18°C
(64°F)		13°C
(55°F)		8°C
(46°F)
Average low3°C
(38°F)		3°C
(38°F)		6°C
(43°F)		9°C
(49°F)		14°C
(58°F)		17°C
(63°F)		21°C
(70°F)		23°C
(74°F)		21°C
(69°F)		16°C
(61°F)		11°C
(51°F)		5°C
(42°F)
Mean minimum-0°C
(31°F)		-0°C
(32°F)		2°C
(36°F)		4°C
(40°F)		10°C
(50°F)		14°C
(58°F)		18°C
(65°F)		20°C
(69°F)		17°C
(63°F)		12°C
(53°F)		5°C
(42°F)		1°C
(35°F)
Minimum-4°C
(26°F)		-1°C
(30°F)		1°C
(34°F)		3°C
(38°F)		9°C
(48°F)		13°C
(56°F)		17°C
(63°F)		18°C
(65°F)		15°C
(60°F)		10°C
(51°F)		4°C
(39°F)		0°C
(33°F)

Compare climate in Iwaki with other places

Compare temperature, precipitation, sunshine, UV index in Iwaki, Japan with other places around the world.

Monthly average precipitation in Iwaki, Japan

Iwaki usually has the most precipitation in July, September and October, with an average of 16 rainy days and 220 mm (8.7 inches) of precipitation per month. The driest months in Iwaki are January, February and December. On average, 58 mm (2.3 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Iwaki. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Average precipitation mm (inches)57 (2.2)45 (1.8)169 (6.6)136 (5.4)154 (6.1)136 (5.3)202 (8.0)137 (5.4)186 (7.3)271 (10.7)85 (3.4)73 (2.9)
Average precipitation days (≥ 1 mm)68101212121713161589

Monthly sunshine hours in Iwaki, Japan

The sunniest months in Iwaki are May, June and August, when the sun shines an average of 9 hours 25 minutes a day. Least sunny months in Iwaki: January, October and December receive an average of 6 hours 37 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Iwaki. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Mean monthly sunshine hours182231265279293280261293247213230219
Mean daily daylight hours9h 55m10h 48m11h 57m13h 8m14h 8m14h 38m14h 23m13h 31m12h 23m11h 12m10h 10m9h 39m

Solar UV radiation in Iwaki, Japan

Iwaki experiences the highest level of ultraviolet (UV) radiation in May, July and August, when the maximum UV index can reach values of 10 - 11, which corresponds to the Very High / Extreme category of sun exposure. January, February and December are in the Moderate exposure category. In these months, the maximum values of the UV index do not exceed 5. For more detailed information, check out our hourly Iwaki UV Index data.

Average daily maximum UV levels by month for Iwaki. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2022 to January 2023.
 JanFebMarAprMayJunJulAugSepOctNovDec
UV Index (month maximum)3579101011119653