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Monthly climate in St Johnston, Ireland

Last updated: July 31, 2025

Under the Köppen–Geiger climate classification St Johnston features a oceanic climate (Cfb). Temperatures typically range between 5 °C (42 °F) and 15 °C (59 °F) through the year, but rarely can drop to -4 °C (25 °F) or can rise to as high as 29 °C (84 °F). The average annual precipitation amounts to about 1216 mm (47.9 inches) and receives 197 rainy days on the 1 mm (0.04 inches) threshold annually. St Johnston enjoys an average of 2929 hours of sunshine throughout the year, and daylight varies from 7 hours 15 minutes to 17 hours 14 minutes per day.

Monthly average temperatures in St Johnston, Ireland

The warmest months in St Johnston are June, July and August, with daily mean temperatures ranging from 13 to 15 °C (56 - 59 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 5 to 6 °C (42 - 43 °F) throughout the day. On average each year, St Johnston experiences 2 days above 25 °C (77.0 °F) and 13 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in St Johnston. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to June 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Maximum14°C
(57°F)		15°C
(59°F)		17°C
(63°F)		21°C
(70°F)		25°C
(78°F)		29°C
(84°F)		28°C
(83°F)		23°C
(74°F)		25°C
(77°F)		19°C
(67°F)		15°C
(59°F)		13°C
(55°F)
Mean maximum12°C
(54°F)		12°C
(54°F)		14°C
(58°F)		18°C
(64°F)		22°C
(72°F)		22°C
(71°F)		25°C
(77°F)		22°C
(72°F)		21°C
(69°F)		17°C
(63°F)		14°C
(57°F)		12°C
(54°F)
Average high7°C
(46°F)		8°C
(46°F)		9°C
(49°F)		12°C
(53°F)		15°C
(59°F)		17°C
(62°F)		18°C
(65°F)		17°C
(64°F)		16°C
(61°F)		12°C
(55°F)		10°C
(49°F)		8°C
(47°F)
Daily mean5°C
(42°F)		6°C
(42°F)		6°C
(44°F)		8°C
(47°F)		11°C
(52°F)		13°C
(56°F)		15°C
(59°F)		15°C
(58°F)		13°C
(55°F)		10°C
(50°F)		7°C
(46°F)		6°C
(43°F)
Average low3°C
(39°F)		3°C
(38°F)		3°C
(38°F)		5°C
(41°F)		7°C
(46°F)		10°C
(50°F)		12°C
(54°F)		12°C
(54°F)		10°C
(50°F)		8°C
(46°F)		5°C
(42°F)		4°C
(40°F)
Mean minimum-2°C
(29°F)		-1°C
(30°F)		-1°C
(30°F)		0°C
(32°F)		2°C
(36°F)		6°C
(43°F)		8°C
(47°F)		8°C
(47°F)		5°C
(42°F)		2°C
(36°F)		1°C
(33°F)		-0°C
(31°F)
Minimum-4°C
(25°F)		-3°C
(27°F)		-4°C
(25°F)		-1°C
(30°F)		-0°C
(32°F)		5°C
(40°F)		7°C
(45°F)		7°C
(45°F)		3°C
(37°F)		1°C
(33°F)		-2°C
(28°F)		-3°C
(28°F)

Compare climate in St Johnston with other places

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

Monthly average precipitation in St Johnston, Ireland

St Johnston usually has the most precipitation in February, August and October, with an average of 18 rainy days and 127 mm (5.0 inches) of precipitation per month. The driest months in St Johnston are January, April and May. On average, 76 mm (3.0 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in St Johnston. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Average precipitation mm (inches)72 (2.8)113 (4.4)106 (4.2)64 (2.5)93 (3.7)107 (4.2)99 (3.9)157 (6.2)97 (3.8)112 (4.4)94 (3.7)103 (4.1)
Average precipitation days (≥ 1 mm)131617131616152016181819

Monthly sunshine hours in St Johnston, Ireland

The sunniest months in St Johnston are May, June and July, when the sun shines an average of 12 hours 40 minutes a day. Least sunny months in St Johnston: January, November and December receive an average of 2 hours 51 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in St Johnston. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Mean monthly sunshine hours6914319831239837738934727722011478
Mean daily daylight hours7h 51m9h 41m11h 53m14h 9m16h 10m17h 14m16h 40m14h 50m12h 39m10h 24m8h 22m7h 15m

Solar UV radiation in St Johnston, Ireland

St Johnston 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 St Johnston UV Index data.

Average daily maximum UV levels by month for St Johnston. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2022 to January 2023.
 JanFebMarAprMayJunJulAugSepOctNovDec
UV Index (month maximum)124568875321