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Monthly climate in Castletown, Ireland

Last updated: July 31, 2025

Under the Köppen–Geiger climate classification Castletown features a oceanic climate (Cfb). Temperatures typically range between 6 °C (43 °F) and 16 °C (61 °F) through the year, but rarely can drop to -5 °C (23 °F) or can rise to as high as 25 °C (78 °F). The average annual precipitation amounts to about 960 mm (37.8 inches) and receives 160 rainy days on the 1 mm (0.04 inches) threshold annually. Castletown enjoys an average of 3173 hours of sunshine throughout the year, and daylight varies from 7 hours 42 minutes to 16 hours 45 minutes per day.

Monthly average temperatures in Castletown, Ireland

The warmest months in Castletown are June, July and August, with daily mean temperatures ranging from 14 to 16 °C (57 - 61 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 6 to 7 °C (43 - 44 °F) throughout the day. On average each year, Castletown experiences 0 days above 25 °C (77.0 °F) and 7 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Castletown. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to June 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Maximum13°C
(56°F)		14°C
(58°F)		15°C
(60°F)		18°C
(65°F)		21°C
(69°F)		25°C
(77°F)		25°C
(78°F)		23°C
(73°F)		23°C
(73°F)		18°C
(65°F)		15°C
(59°F)		13°C
(56°F)
Mean maximum12°C
(53°F)		13°C
(55°F)		14°C
(57°F)		16°C
(61°F)		19°C
(67°F)		21°C
(70°F)		23°C
(74°F)		21°C
(71°F)		21°C
(70°F)		17°C
(63°F)		14°C
(58°F)		13°C
(55°F)
Average high8°C
(47°F)		9°C
(48°F)		10°C
(50°F)		11°C
(53°F)		14°C
(58°F)		17°C
(63°F)		19°C
(67°F)		18°C
(65°F)		17°C
(62°F)		13°C
(56°F)		10°C
(51°F)		9°C
(48°F)
Daily mean6°C
(43°F)		6°C
(44°F)		7°C
(45°F)		8°C
(47°F)		11°C
(52°F)		14°C
(57°F)		16°C
(61°F)		15°C
(60°F)		14°C
(57°F)		11°C
(52°F)		8°C
(47°F)		7°C
(44°F)
Average low4°C
(39°F)		4°C
(39°F)		4°C
(39°F)		5°C
(42°F)		8°C
(46°F)		11°C
(52°F)		13°C
(55°F)		13°C
(55°F)		11°C
(51°F)		8°C
(47°F)		6°C
(43°F)		5°C
(41°F)
Mean minimum-1°C
(30°F)		-1°C
(31°F)		-1°C
(31°F)		0°C
(33°F)		2°C
(36°F)		7°C
(45°F)		9°C
(48°F)		9°C
(48°F)		5°C
(42°F)		3°C
(38°F)		1°C
(34°F)		-0°C
(32°F)
Minimum-2°C
(28°F)		-3°C
(28°F)		-5°C
(23°F)		-2°C
(29°F)		1°C
(33°F)		6°C
(43°F)		7°C
(45°F)		7°C
(45°F)		3°C
(37°F)		1°C
(34°F)		0°C
(33°F)		-2°C
(28°F)

Compare climate in Castletown with other places

Compare temperature, precipitation, sunshine, UV index in Castletown, Ireland with other places around the world.

Monthly average precipitation in Castletown, Ireland

Castletown usually has the most precipitation in August, November and December, with an average of 14 rainy days and 103 mm (4.1 inches) of precipitation per month. The driest months in Castletown are January, April and June. On average, 58 mm (2.3 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Castletown. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Average precipitation mm (inches)53 (2.1)87 (3.4)79 (3.1)55 (2.2)70 (2.8)67 (2.6)68 (2.7)96 (3.8)76 (3.0)93 (3.6)108 (4.3)107 (4.2)
Average precipitation days (≥ 1 mm)101515111213131513141514

Monthly sunshine hours in Castletown, Ireland

The sunniest months in Castletown are May, June and July, when the sun shines an average of 13 hours 18 minutes a day. Least sunny months in Castletown: January, November and December receive an average of 3 hours 38 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Castletown. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Mean monthly sunshine hours91154211323409403410365312247133108
Mean daily daylight hours8h 14m9h 53m11h 54m13h 58m15h 47m16h 45m16h 14m14h 36m12h 36m10h 33m8h 41m7h 42m

Solar UV radiation in Castletown, Ireland

Castletown experiences the highest level of ultraviolet (UV) radiation in June, July and August, when the maximum UV index can reach values of 7 - 8, which corresponds to the High / Very High category of sun exposure. January, February and December are in the Low exposure category. In these months, the maximum values of the UV index do not exceed 2. For more detailed information, check out our hourly Castletown UV Index data.

Average daily maximum UV levels by month for Castletown. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2022 to January 2023.
 JanFebMarAprMayJunJulAugSepOctNovDec
UV Index (month maximum)124578875421