Ireland's climate is significantly warmer than almost all other locations at similar latitude, such as Poland (on the continent) or Newfoundland (on the opposite edge of the Atlantic), due to the warming influence of the North Atlantic drift. The prevailing wind blows from the southwest, breaking on the high mountains of the west coast.

Please check out http://www.ireland.com/travelnow/weather/ for the latest weather in Ireland.

Rainfall is therefore a particularly prominent part of western Irish life, with Valentia Island, off the west coast of County Kerry, getting almost twice as much annual rainfall as Dublin on the east (1400 mm vs. 762 mm). Across the country, about 60% of the annual rainfall occurs between August and January.

January and February are the coldest months of the year, and mean daily air temperatures fall between 4 and 7 °C during these months. July and August are the warmest, with a range of 14 to 16 °C. The sunniest months are May and June, with an average of five to seven hours sunshine per day.[26] Though extreme weather events in Ireland are comparatively rare when compared with other countries in the European Continent, they do occur.

Explosive Atlantic depressions, occurring mainly in the months of December, January and February, can occasionally bring winds of up to 160 km/ph (100 mph) to Western coastal counties; while the summer months, and particularly around late July/early August, sudden and violent thunderstorms can develop, more especially, but not exclusively, across midland and western areas of the country.

The table shows mean climate figures for the Dublin Airport weather station over a thirty-year period. Climate statistics based on the counties of Northern Ireland vary slightly but are not significantly different.

from wikipedia.com