Summer of 2010 was warm but Summer of 2011 could be the coldest in decades.
The reason for the generally cooler than average conditions this summer so far is due to fact that most of weather this during June, July and August has come in from the north Atlantic,
usually in the form of Polar Maritime (Pm) air masses which have been unusually dominant this season thus far (particularly so the P5 and P6 strand) and which is the direct result of
the polar jet stream running much further south than normal over the North Atlantic region throughout much of the season.
http://www.irishweatheronline.com/news/ireland-on-track-for-coldest-summer-in-at-least-25-years/32228.html