Weather in Wicklow
Ireland's climate is dominated by the Atlantic Ocean. Mild damp summers and cool wet winters are the normal fare but the weather patterns are ever changing and never totally predictable. In general, Irish winters are cold and wet, and Irish summers are warmer and drier. But, any weather is possible at any time, and the saying ‘four seasons in one day’ often does apply. Irish people are used to constant change, and dress accordingly – no matter how clear it looks, always bring a jacket.
It is important to check the weather forecast before visiting the National Park, but visitors should never trust any weather forecast beyond the following 24 hours, and even then the weather can catch forecasters out. Always bring some extra layers of clothing.
Be aware also, that weather is always more severe in the mountains. As one gains height, temperatures drop, wind chill increases, and rain and snow is more likely.
Ireland is well known for its rain. Ireland is an island in the North Atlantic on the edge of Europe. It experiences warm temperatures for its latitude (53° N) due to the influence of the Gulf Stream current that brings warm water from the Mexican Gulf. The prevailing wind also comes from this direction, so the combination of warm, wet air brings lots of precipitation. Two days out of three are rainy on the west of Ireland, and one day out of three is rainy on the east coast of Ireland.
Rain is more frequent in winter, but rain can be expected at any time of the year. Annual rainfall reaches 2000mm on the highest summits. Moist air that is forced to rise over mountains will generate rain or snow depending on the temperatures. A mountain top that seems clear can quickly become enshrouded in cloud.
Wind is an important feature, especially on the higher hills where tree growth is often limited. Dominant wind directions are from the south and west, however there are times each year when an easterly airflow brings both snow and ice from the European continent. This unending drama of weather is a factor that makes any day in Wicklow a 'unique' day.
Summer weather can happen anytime between May and September, but Irish summers can be hit and miss and can vary dramatically from year to year and from day to day. Wicklow's position near the south east corner of Ireland gives it a relatively high incidence of bright sunshine, averaging about 4 hours a day over the entire year. In a good summer, temperatures of 20-25°C can be expected, with little or no wind or rain. More likely, temperatures of 15-20°C are normal, with frequent showers and a fresh breeze. Temperatures will be 5-10°C cooler in the mountains.
Winters generally are wet and windy, with some cold clear days and some cold spells often during January and February. Unless it is a particularly cold winter, the temperatures rarely dip below zero during the day. Frosty or icy conditions are usually associated with high pressure systems stabilising over the country, but normally we experience a series of low pressures systems sweeping in from the Atlantic Ocean bringing the familiar wet and windy weather.
Snow cover in winter increases with altitude and can reach an average of 30 days a year on some of the highest peaks.
Some Facts & Figures
Highest Temperature: 33°C in Kilkenny in 1887
Lowest Temperature: Minus 19°C in Sligo in 1881
Strongest Wind (sea level): 124 mph (198 km/h) in Kilkeel, Co Down 1974
Sunshine: Ireland gets from 1,400 to 1,700 hours per year of sunshine (compared to 4,300 in the Sahara). May and June are the sunniest months with 5-6.5 hrs per day, and December is the dullest with between 1-2 hours per day.