Ireland's cold spell explained

The situation we find ourselves in now is no different to what we experienced in January and December 2010 in terms of a blocking setup with high pressure to our northeast/north feeding in cold air that can be traced back all the way to Siberia and ultimately the Arctic. The result of this blocking setup has been to shift the jetstream further south over Iberia and North Africa bringing these areas the cooler westerlies and showers that we would be more accustomed to at this time of year. In fact, the week just gone has seen Ireland experience its coldest 7-day period since January 2010. Obviously, the prolonged nature of this cold spell would have resulted in much more widespread, severe conditions had the spell occurred during the peak winter months.

Down through history, Ireland has experienced blasts of wintry weather late into the Celtic spring season. The early months of 1947 saw one of the most persistent cold spell of the century, with snowfalls affecting all parts of the country from late January until mid-March. In 1908, much Leinster and east Munster was affected by heavy snow in late April. In mid-March 1886, a great blizzard with snow depths up to 60cm struck Ulster.  A couple of weeks later between April 7th and 10th there was heavy snow, especially in the West and Midlands.

On average, Malin Head in Donegal records 2.3 days of lying snow each April compared to 2.0 in Mullingar (Westmeath) and 1.9 in Claremorris (Mayo). Snow has also been reported in May and September. On some of these occasions the falls have been considerable but the snow melted quickly. Interestingly, Clones in Monaghan records 0.4 snow days each May according to Met √Čireann's official figures for the period 1980-2011.

There is no evidence to suggest that the current setup is related to climate change as such a conclusion would have to be based on similar weather conditions occuring annually or at least prevailing over an extended period of time.

This week will bring a slow rise in temperatures but overall it will remain a few degrees colder than we would expect for this time of year. The jetstream looks like it will find itself in a more familiar position over Ireland and Britain within 7-10 days which means a return to a westerly/southwesterly setup with rain at times.  There is no indication yet as to what the summer will bring Ireland weatherwise.