Why has much of Ireland had no sun for 10 days now? The jet stream is to blame

Jet stream is to blame, with a blocking system shutting out the sun

Some areas have had zero hours of sunshine over the past seven days. Photograph: Alan Betson/The Irish Times
Some areas have had zero hours of sunshine over the past seven days. Photograph: Alan Betson/The Irish Times

Much of Ireland has been stuck under gloomy, grey clouds for the past 10 days, ensuring no sunshine in many locations.

In some places there was no sunshine at all for several days, particularly in the eastern half of the country, according to real-time data from Met Éireann weather stations.

Dublin Airport has had zero hours of sunshine in the past seven days – not a record but a highly unusual occurrence.

The gloomy weather coincides with a combination of low wind, a dominant high-pressure system in northwestern Europe in recent weeks and easterly breezes, which can lead to persistently grey skies.

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The cause is the jet stream which since the first week of February has been flowing far north of Ireland. This pattern in the upper atmosphere has allowed a large, slow-moving area of high pressure to build over Scandinavia and has led to a cool air mass heading our way.

While high pressure generally brings dry and settled conditions, it can also trap cloud and moisture – especially at this time of year when the winds are blowing over a cold North Sea.

This type of “buckled” shape in the jet stream is known as a blocking pattern and it can slow or halt the progression of rain-bearing weather fronts, diverting them elsewhere – especially Atlantic rain systems.

Alan O’Reilly of social media account Carlow Weather said on X that Dublin Airport has had zero hours of sunshine in the past seven days – not a record but a highly unusual occurrence.

With a lack of sunshine on Monday at the airport, we’re now on to day eight without sunshine.

Dublin Airport has had zero hours of sunshine in the last seven days but Belmullet has had 19.1 hours! Cork just 2.7 hours and Johnstown Castle in Wexford 0.7 hours," he tweeted.

“In other words, the stats confirm what a lot [are] saying, sick of cloud, where is the sun hiding? Sadly not a lot of sunshine forecast this coming week either but some spells here and there,” Carlow Weather said on Monday.

The persistent gloom hanging over Ireland and the UK could come to an end this week, with a little sunshine set to return coinciding with warmer conditions and a series of Atlantic weather fronts crossing the country, forecasters say.

In January, the number of dull days ranged from 10 days at Malin Head, Co Donegal, to 14 days at Johnstown Castle, Co Wexford. A dull day is a day with less than half an hour of sunshine.

Ireland normally gets between 1,100 and 1,600 hours of sunshine each year. The sunniest months are May and June. During these months, sunshine duration averages between 5 and 6.5 hours per day over most of the country.

The extreme southeast gets most sunshine, averaging over seven hours a day in early summer.

December – rather than February – is usually the dullest month, with average daily sunshine ranging from about one hour in the north to almost two hours in the extreme southeast.

Kevin O'Sullivan

Kevin O'Sullivan

Kevin O'Sullivan is Environment and Science Editor and former editor of The Irish Times