Temperatures are set to rise sharply over the coming days after what has been an unusually cold May, though a heatwave under Met Éireann’s parameters is unlikely to occur.
The warm weather expected from Saturday, and through the first half of next week at least, is instead being described by the forecaster as a “warm spell”.
Temperatures could possibly breach 25 degrees in some areas from Monday, but the location of the peak heat is expected to change as a high pressure system moves across the country.
A heatwave is defined by Met Éireann as five or more consecutive days where temperatures of 25 degrees and above are observed at a single weather station.
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“The locations where we’ll see temperatures possibly over 25 degrees are changing, so we’re unlikely to meet the criteria for a heatwave with this particular spell,” Met Éireann’s Ailís Hankinson said.
She said the forecast suggests the “warm spell” will continue throughout the first half of the week, but “uncertainty increases towards the latter half”.
Temperatures are set to trend upwards from Saturday, with warm or “very warm” conditions expected to follow. Highs of between 17 and 23 degrees are expected on Saturday, with Leinster due to experience the warmest conditions.
Sunday is forecast to be another warm and sunny day, with highest temperatures of 18 to 22 degrees, though cloudier skies will remain over the northwest until the evening.
Temperatures are then expected to reach 25 degrees and possibly exceed that from Monday onwards.
With just over a week until June begins, a heatwave next week, though unlikely, would be the first to ever occur in Ireland during the spring. Ireland’s last heatwave came in September 2023.
There is also expected to be unseasonably warm weather in the Britain over the coming days, with some parts forecast to enter official UK heatwave territory. That threshold, however, is three rather than five consecutive days exceeding 25 degrees in the case of Scotland and Northern Ireland, or 28 degrees in London.
Temperatures in France, Spain and Portugal are also expected to breach 30 degrees over the coming days.
Heatwaves have become more frequent and intense globally since the 1950s, with human-caused climate change being the main driver, according to Met Éireann.
The forecaster said it would have been “virtually impossible” for some recent global heatwaves to occur without human influence on the climate system.
Climate change has also been cited as a reason for Ireland having its warmest summer on record last year.
