Eight countries in Europe saw record temperatures at the start of the New Year, including northern Spain, where the mercury reached 25C in Bilbao.
Climatologist and Professor Emeritus of Geography at Maynooth University John Sweeney said it has been "an exceptional" start to 2023.
Speaking on RTÉ's Morning Ireland, he said: "If you were to take a line from Denmark down to Venice on an average January day everywhere east of that will be below zero. And in fact what we've been seeing have been temperatures enormously greater than that.
"We've been seeing temperatures of 19 degrees centigrade in Warsaw, 16 in Berlin and equally high temperatures over much of the Czech Republic, the Netherlands, Lithuania and Latvia. And really, it's an exceptional event which has extended all the way down to northern Spain, where Bilbao had about 25 degrees centigrade".
Prof Sweeney said that what has been happening is that a plume of warm air, which originated over the west coast of Africa, has caused a lot of depressions over the past week and that has been driving air from the south into Europe.
He said that normally that would not cause these exceptionally high temperatures, but it has been exacerbated this time by two other things happening at the same time: a very strong anticyclone that has developed over eastern Europe, which has been driving air from the southwest over much of the continent, and the jet stream has been "plunging away to the south over North America but plunging away to the north over Europe."
Prof Sweeney said Ireland missed out on the warmer weather, as it is too far to the north and to the west.
He said extremes of climate of this nature are becoming the new norm and something people are going to have to learn to live with.
"We know that the first harbinger of climate breakdown, is the increased frequency of extremes. Now we won't see this kind of an event happening year or maybe even every ten years, because it's such an exceptional event that we've seen in the past few days over Europe.
"But we can expect to see those kinds of temperature extremes and for Ireland in particular, rainfall extremes becoming more common as the oceans around us warm up, as the land around us warms up and the air can hold more water vapor, in the case of Ireland, and of course it will bring more tropical air into Europe as well, so it has consequences for us."