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Monthly climate in Iyo, Japan

Last updated: July 31, 2025

Under the Köppen–Geiger climate classification Iyo features a humid subtropical climate (Cfa). Temperatures typically range between 5 °C (42 °F) and 27 °C (81 °F) through the year, but rarely can drop to -4 °C (24 °F) or can rise to as high as 33 °C (91 °F). The average annual precipitation amounts to about 1900 mm (74.8 inches) and receives 144 rainy days on the 1 mm (0.04 inches) threshold annually. Iyo enjoys an average of 3181 hours of sunshine throughout the year, and daylight varies from 9 hours 56 minutes to 14 hours 20 minutes per day.

Monthly average temperatures in Iyo, Japan

The warmest months in Iyo are July, August and September, with daily mean temperatures ranging from 24 to 27 °C (75 - 81 °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, Iyo experiences 87 days above 25 °C (77.0 °F) and 9 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Iyo. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to June 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Maximum15°C
(59°F)		19°C
(67°F)		20°C
(69°F)		24°C
(75°F)		28°C
(82°F)		30°C
(86°F)		33°C
(91°F)		33°C
(91°F)		33°C
(91°F)		29°C
(84°F)		25°C
(77°F)		22°C
(71°F)
Mean maximum13°C
(56°F)		15°C
(59°F)		19°C
(67°F)		23°C
(73°F)		27°C
(80°F)		28°C
(82°F)		32°C
(90°F)		33°C
(91°F)		31°C
(88°F)		27°C
(82°F)		22°C
(72°F)		17°C
(63°F)
Average high9°C
(48°F)		9°C
(49°F)		14°C
(57°F)		18°C
(64°F)		22°C
(72°F)		25°C
(77°F)		28°C
(83°F)		30°C
(87°F)		27°C
(80°F)		22°C
(72°F)		17°C
(62°F)		11°C
(52°F)
Daily mean5°C
(42°F)		6°C
(43°F)		10°C
(50°F)		14°C
(57°F)		18°C
(65°F)		22°C
(72°F)		26°C
(79°F)		27°C
(81°F)		24°C
(75°F)		19°C
(66°F)		13°C
(55°F)		8°C
(46°F)
Average low3°C
(37°F)		3°C
(37°F)		6°C
(43°F)		10°C
(50°F)		15°C
(59°F)		19°C
(66°F)		23°C
(74°F)		25°C
(76°F)		21°C
(70°F)		16°C
(60°F)		9°C
(49°F)		4°C
(40°F)
Mean minimum-1°C
(30°F)		-1°C
(30°F)		1°C
(34°F)		4°C
(39°F)		9°C
(48°F)		15°C
(60°F)		21°C
(69°F)		22°C
(71°F)		16°C
(61°F)		10°C
(50°F)		3°C
(38°F)		0°C
(33°F)
Minimum-4°C
(25°F)		-4°C
(24°F)		0°C
(33°F)		2°C
(36°F)		7°C
(44°F)		14°C
(57°F)		18°C
(65°F)		20°C
(68°F)		14°C
(58°F)		8°C
(47°F)		3°C
(37°F)		-1°C
(31°F)

Compare climate in Iyo with other places

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

Monthly average precipitation in Iyo, Japan

Iyo usually has the most precipitation in June, July and September, with an average of 16 rainy days and 267 mm (10.5 inches) of precipitation per month. The driest months in Iyo are January, November and December. On average, 63 mm (2.5 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Iyo. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Average precipitation mm (inches)60 (2.4)90 (3.6)129 (5.1)135 (5.3)153 (6.0)215 (8.5)374 (14.7)197 (7.7)212 (8.4)204 (8.0)61 (2.4)69 (2.7)
Average precipitation days (≥ 1 mm)9111210111419151510810

Monthly sunshine hours in Iyo, Japan

The sunniest months in Iyo are April, May and August, when the sun shines an average of 9 hours 51 minutes a day. Least sunny months in Iyo: January, February and December receive an average of 7 hours 12 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Iyo. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Mean monthly sunshine hours191237273288304283287313268260244227
Mean daily daylight hours10h 10m10h 57m11h 58m13h 1m13h 54m14h 20m14h 7m13h 21m12h 21m11h 18m10h 24m9h 56m

Solar UV radiation in Iyo, Japan

Iyo experiences the highest level of ultraviolet (UV) radiation in May, July and August, when the maximum UV index can reach values of 12 - 12, which corresponds to the Extreme category of sun exposure. January, February and December are in the Moderate / High exposure category. In these months, the maximum values of the UV index do not exceed 6. For more detailed information, check out our hourly Iyo UV Index data.

Average daily maximum UV levels by month for Iyo. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2022 to January 2023.
 JanFebMarAprMayJunJulAugSepOctNovDec
UV Index (month maximum)469101211121211864