Ireland has an oceanic climate (Köppen climate classification Cfb), with cool and damp conditions throughout the year. Summers are warm, and winters are cold. Ireland is an island nation in northwestern Europe in the North Atlantic Ocean. The Republic of Ireland occupies five-sixths of the portion of the island, while Northern Ireland occupies the rest. The Irish Sea and North Channel separate Ireland from Great Britain in the east. The Atlantic Ocean lies to the north and west, and the Celtic Sea is in the south. The Atlantic Ocean and the warm Gulf Stream current chiefly influence the climate.
Ireland, the Emerald Isle, lies in the high latitudes between 51°N and 56°N but is devoid of extreme temperatures. The mild climate and frequent rainfall produce lush green vegetation, and woodlands occupy a significant area of the island. Much of the terrain is low-lying, and even the mountains do not rise to great heights. The Shannon, Ireland’s longest river at 240 miles, rises in Ulster, bisects the island, and flows in the Atlantic Ocean south of Limerick. The southeastern region of Leinster has the most fertile land in the country. The western coasts are mountainous and rocky, with many islands, peninsulas, and bays. Coastal mountains bound the low plains that span the center of the island. The highest point in Ireland is Carrauntoohil at 1047 meters.
Moist winds from the Atlantic Ocean moderate the climate of Ireland to prevent extreme temperatures that are standard at similar latitudes in other parts of the world. Summers are mild, with high temperatures rarely above 25°C (77°F) at the peak of July. The inland areas are warmer than the coast, but temperature differences are low over the island. The Atlantic weather fronts result in unstable weather, with alternate periods of rain and shine. Extended periods of clear skies are rare, and running clouds are a common sight. Winters are cold, but temperatures below freezing do not last for many nights. The western coasts are milder than the interior in the winter, but the temperature difference is hardly -15°C (5°F). Cold waves are short-lived due to the influence of the westerlies. Snow and frost occur for a few days in the winter in a few places. Temperatures below freezing occur for an average of 20 days in the year in Dublin and 50 days in the inland regions. Spring is cold initially and becomes mild by May. The spring season is the driest and sunniest part of the year. Autumn is cloudy, rainy, and windy, with little sunshine.
The annual rainfall in Ireland is in the ample range of 762mm (30") to 1524mm (60"). The precipitation occurs throughout the year, with the maximum during late autumn and winter seasons. The slopes of the western hills receive the highest rainfall of over 2032mm (80") annually. Dublin, the capital on the east coast, registers only 762mm (30") of rain. Ireland receives moderate sunshine between 1000 to 1500 hours annually. The Ulster area in the north receives hardly 1200 hours, while the Munster area in the south registers 1400 hours of annual sunshine. Wexford and Waterford, in the southeast, are the sunniest places in Ireland with more than 1570 hours of annual sunshine. The northwestern shores are the windiest places between late autumn and early spring. The western coasts are prone to Atlantic storms, with destructive winds and heavy rainfall.
The highest recorded temperature in Ireland is 33.3°C (91.9°F), set on June 26, 1881, in Kilkenny Castle, Kilkenny. The lowest recorded temperature of -19.1°C (-2.4°F) occurred on January 16, 1881, in Markree Castle, Sligo. Ballaghbeena Gap recorded the highest annual rainfall of 3964.9mm (156.1") in Ireland.
The best time to visit Ireland
The best time to visit Ireland is during the summer season from June to August. Temperatures are at the warmest of the year during the summer, with ample sunshine. The southeastern region is the sunniest, with long days and average highs above 20°C (68°F). The mild period sees moderate rainfall under partly cloudy skies. The days are occasionally cold in June, but July and August are pleasantly warm. Seawaters near Dublin are at their warmest of the year between 12.8°C (55°F) to 16.1°C (61°F). May and September have acceptable temperatures, but the skies are often cloudy, and the days are short. Irish summers need a jacket or sweater, raincoat or umbrella.
The worst time to visit Ireland
The worst time to visit Ireland is during the cold winter season from December to February. The sunshine hardly lasts for 2 to 3 hours, and the skies are mostly cloudy. The northern regions are cold, with freezing nights and day temperatures in the 7.2°C (45°F) to 10°C (50°F) range. Frost is standard, but snow is rare. The winter is susceptible to low-pressure systems that bring windstorms in the north. The western region sees ample rainfall and little sunshine in the winter. Cold waves are rare, but the conditions are cloudy and wet most of the time. Stormy conditions occasionally occur in late autumn and winter seasons.
Ireland has few natural weather hazards in the form of earthquakes, sinkholes, landslides, floods, and volcanic ash. Major landslides in Galway and Mayo in 2003 damaged roads and buildings, and were responsible for substantial financial losses. The eruption of Eyjafjallajökull volcano in Iceland in 2010 affected the atmosphere of Ireland due to the spread of volcanic ash. Geohazards, such as sinkholes, cause engineering problems due to sudden collapse associated with subsurface voids. Moderate-intensity earthquakes mainly occur near Donegal and Wexford, in the southeast and northwest regions of Ireland. Floods occasionally occur in the western region. Atlantic depressions occasionally bring winds with speeds up to 160.9km/h (100mph) on the west coast.
Weather in January
January is usually the coldest month of the year in Ireland, with gray skies and damp conditions. Temperatures seldom drop below -5°C (23°F) in the winter. The average temperatures in Dublin, on the east coast, are in the cold zone of 2.2°C (36°F) to 7.8°C (46°F). Valentia on the southwest coast has mild winters, with temperatures in the range of 5°C (41°F) to 10°C (50°F), and at 175.3mm (6.9"), is twice as wet as Dublin. The skies are often cloudy, with hardly a couple of hours of daily sunshine. The Wicklow Mountains receive daily snowfall in January, but most low-lying areas rarely see snow on the ground. Malin Head, the northernmost point in Ireland, registers 99.1mm (3.9") of rainfall, and average wind speeds up to 32.2km/h (20mph). Temperatures in County Donegal remain in the cold range of 3.9°C (39°F) to 7.8°C (46°F), with little sunshine. Fog is a companion during early morning flights from Cork Airport in the winter. Expect an average of 10 days of frost in northern regions of Ireland in January.
Weather in February
February is cold and damp in the winter of Ireland, with little sunshine amid mostly cloudy skies. Dublin is in the cold zone of 2.2°C (36°F) to 8.3°C (46.9°F), but calmer than the northern coast, with wind speeds below 24.1km/h (15mph). The east coast receives an average of 63.5mm (2.5") of precipitation and is less rainy than the west coast. Seawater temperatures below 7.8°C (46°F) in Dublin are not ideal for swimming. The Irish Sea is cold, and the east coast is also not favorable for swimming in the winter. The days are short and gradually increase from 9 hours in the beginning to 10.5 hours by the end of the month. Frost is standard in the northern regions, but snowfall is occasional. Mornings are foggy and mostly wet. Pack a sweater and a rain jacket for protection from wind, cold, and rain. February sees 2 to 3 hours of sunshine in much of Ireland and is generally not a good time to visit Ireland.
Weather in March
March begins with cold, damp weather in Ireland, with occasional freezing nights. The beginning of the spring season by the Spring Equinox ushers warm days with high temperatures over 10°C (50°F). The average temperatures in Dublin are in the cold to the mild zone of 2.8°C (37°F) to 10°C (50°F) range, with daily sunshine of 4 hours. Light rainfall frequently occurs, with cloud cover for 60% of the day. Shannon registers average temperatures in the 4.4°C (39.9°F) to 11.1°C (52°F), with 78.7mm (3.1") of rainfall. It is not until late March that the weather gears for the outdoor season. Rosslare, in Wexford, records average temperatures in the zone of 4.4°C (39.9°F) to 10.6°C (51.1°F), with a slight decrease in precipitation to 68.6mm (2.7"). The daylight lasts between 11.5 to 12 hours in much of Ireland, with weak sunshine of 3 to 4 hours. Wind speeds are in the range of 22.5km/h (14mph) to 29km/h (18mph) in the extreme north and western shores. Rain jackets are necessary during outdoor activities in March in Ireland.
Weather in April
April begins to show signs of warmth in Ireland, as the spring season advances rapidly. The striking feature is the increase in daylight from 13 to 15 hours by the end of the month. The average temperatures in Dublin are in the 5°C (41°F) to 12.2°C (54°F), with 5 hours of daily sunshine that promotes outdoor activities. Wind speeds remain between 19.3km/h (12mph) and 22.5km/h (14mph) on the eastern shores, but the Irish Sea is cold for swimming below 8.9°C (48°F). Malin Head is slightly cold between 6.1°C (43°F) to 11.1°C (52°F) and windy. April sees 11 to 14 wet days in Ireland, and the skies are cloudy for at least 50% of the time. Although the sun rises by 6 a.m., the best time to be outdoors is in the mid-morning and afternoon. Snowfall ceases in the Wicklow Mountains, and little snow remains on the ground. Frost and fog are no more a concern. April is a shoulder season month with fair weather to visit Ireland.
Weather in May
May is mild to warm in Ireland amid a rapid increase in daylight and sunshine. The landscape is lush green as periodic light rainfall is standard, even during sunny days. The ordinarily wet west coast of Valentia records 94mm (3.7") as average temperatures warm in the 7.8°C (46°F) to 15°C (59°F) zone. Cork and Clones register temperatures between 6.7°C (44.1°F) to 15°C (59°F), with 63.5mm (2.5") to 76.2mm (3"), and slightly cold nights. The southeast is the best region for outdoor activities, with 15 to 16.5 hours of daylight and 6 hours of daily sunshine. The seawaters are cold below 10°C (50°F) on the shores of the Atlantic and the Irish Sea. The relative humidity is in the comfortable zone of 55 to 65%, even with a consistent cloud cover for 50% of the time. Nights are occasionally cold but rarely drop below freezing. Sweaters and jackets serve well post afternoon hours. Expect a surge in tourist numbers by late May in Ireland with the increase in sunshine.
Weather in June
June begins the lovely summer season in Ireland, with long days and comfortable sunshine. June 21 is the longest day of the year, with an incredible 17 hours of daylight and sunset past 10 p.m. The skies are partly cloudy, and the warm sunshine hardly registers an ultraviolet index of 6. Bellmullet in County Mayo, registers average temperatures in the mild 10.6°C (51.1°F) to 16.1°C (61°F), with 71.1mm (2.8") of moderate rainfall in 8 to 10 wet days. Limerick has slightly cold nights and is in the range of 10°C (50°F) to 17.2°C (63°F). Kilkenny in the southeast has warm days and cold nights, with average temperatures in the 9.4°C (48.9°F) to 18.3°C (64.9°F). Valentia is relatively dry, with 12 wet days in June that attracts visitors to the west coast. The average wind speeds are between 16.1km/h (10mph) to 19.3km/h (12mph), with the standard direction from the west. A light jacket is useful for protection from sudden showers, although they last briefly. June is cool and pleasant in Ireland, but expect crowds and sky-high rates.
Weather in July
July is warm and pleasant in the summer of Ireland. Temperatures reach yearly-highs but rarely go past 25°C (77°F) and seldom beyond 30°C (86°F). The average temperatures in Dublin are in the warm 12.2°C (54°F) to 20°C (68°F) range, with a 50% probability of cloudy skies and 5 hours of daily sunshine. County Donegal sees a drop in wind speeds and rainfall to 94mm (3.7"), with 14 wet days in July. Birr and Mullingar in Leinster, register average temperatures in the 11.1°C (52°F) to 19.4°C (66.9°F) range. It is advisable to pack a sweater or light jacket as even the warmest month of the year has cold nights. Chances of occasional showers remain constant at 28% in Dublin in the month. The daylight begins to decrease by the second half of July to register 15.5 hours by the month-end. The comfortable July weather is a respite from the standard cold and damp weather in Ireland over the rest of the year.
Weather in August
August is warm and beautiful in the summer season of Ireland, with frequent sunshine and light precipitation. Wexford and Galway register average temperatures in the comfortable zone of 12.2°C (54°F) and 18.9°C (66°F). The daylight decreases sharply to register below 14 hours at the end of the month. Evenings are cool and nights tend to be cold, which make a sweater or light jacket a useful accessory. Much of Ireland receives between 2“ to 76.2mm (3") of rainfall except for the west coast, which registers 101.6mm (4") to 127mm (5"). The Irish Sea waters on the southeast coast are at the warmest average temperatures of 16.1°C (61°F) during the year and attract water activities. Wind speeds between 16.1km/h (10mph) to 19.3km/h (12mph) keep the air on the shores fresh as humidity levels remain in the 55 to 60% zone. Summer air increases the appetite for an afternoon tea during outdoor activities. Expect warm sunshine of 5 hours a day in most regions of Ireland in August.
Weather in September
September is cool in Ireland after the departure of the summer season. The daylight recedes gradually from 13 hours in the beginning to 11.5 hours at the end of the month. The average temperatures in Dublin are in the range of 10°C (50°F) to 17.2°C (63°F), with hardly 4 hours of sunshine. Kilkenny registers between 8.9°C (48°F) to 17.8°C (64°F), with comfortable days but cold nights. Malin Head is windy and damp, with 99.1mm (3.9") of rainfall in 16 wet days in September. The northern coastal region sees temperatures in the zone of 11.1°C (52°F) and 16.1°C (61°F) and is colder than the south by a few degrees. The autumn season brings cloudy skies to Ireland, with overcast conditions up to 60% of the time. Cold weather often follows sunny days, and the conditions are generally unstable. Pack warm clothes and add a rain jacket to counter the cold and wet weather. The attraction of the fall season does not allow tourist numbers to recede significantly in September in Ireland.
Weather in October
October is cold in the fall season of Ireland, with decreasing sunshine amid short days. The daylight drops below 10.5 hours in most regions by the end of the month. The average temperatures in Limerick and Kerry are in the cold range of 7.2°C (45°F) to 12.8°C (55°F), with only 3 hours of daily sunshine. Shanon and Roches Point in the Munster region register slightly high temperatures between 8.3°C (46.9°F) to 14.4°C (57.9°F), with at least 16 wet days in the month. Dublin seawaters are cold below 13.9°C (57°F) and not suitable for swimming. Much of the country sees at least 15 wet days in October, with little room for sunshine. Valentia registers up to 177.8mm (7") of rain, as the western coasts receive abundant rainfall. The northern coast is exceptionally windy, with average speeds above 24.1km/h (15mph). Wear warm clothes during outdoor activities or a walk in the colorful autumn landscape. Expect mild sunshine, breezy evenings, and cold nights in October in Ireland.
Weather in November
November is cold and wet, with the departure of the fall season in Ireland. The daylight fades quickly from 10.5 hours to 8.5 hours at the end of the month. Cloudy skies allow daily sunshine for less than 2 hours. The average temperatures in the Ulster region are in the 3.9°C (39°F) to 10.6°C (51.1°F), with occasional freezing nights. Snowfall is rare, but frost is standard in many places. The late sunrise past 7.30 a.m. and the damp conditions make the mornings foggy. Dublin registers average temperatures in the 5°C (41°F) to 10°C (50°F) range, with cloudy skies 63% of the time. The average rainfall is between 76.2mm (3") to 152.4mm (6"), with the southwest coast, particularly rainy. Strong winds often blow on the northern and western shores, and seawater temperatures remain below a cold 12.2°C (54°F). Wear warm clothes and pack a jacket for rain protection. Budget travelers can take advantage of the drop in prices due to cold weather in November in Ireland.
Weather in December
December is the beginning of the cold and wet winter season in Ireland. Snowfall occurs in the mountains but is rare in central lowlands. The average temperatures in Kilkenny are in the cold zone of 2.2°C (36°F) to 8.9°C (48°F), with 91.4mm (3.6") of rain that limits the daily sunshine to just 2 hours. Valentia has mild conditions between 5°C (41°F) to 11.1°C (52°F) but receives 165.1mm (6.5") of precipitation in 20 wet days in the month. The northern coasts are windy and humid, with average wind speeds in the 18km/h (11.2mph) to 32.2km/h (20mph) range. Check the weather forecast before going to Donegal, which is the windiest area in the winter. The possibility of rain is at least 40% in Dublin in December, as the skies are overcast more than 65% of the time. The shortest days of the year occur in the second half of December, with only 7.5 to 8 hours of daylight. December weather is generally unfavorable for a visit to Ireland.