More seasonable weather on the way - 24th September 2021

After a very mild September so far, temperatures will take a noticeable dip early next week as a cold polar maritime airmass arrives across Ireland.

So far this month it has been very mild, dry and calm, with all weather stations across Ireland reporting temperatures 1.5 to 2.7°Celsius above the September average.  The above average temperatures will continue into the weekend due to a mild, tropical maritime airmass, however through the second half of Sunday a much cooler, polar maritime airmass will push in across Ireland, introducing more seasonal temperatures.

Forecast pressure and airmass chart for Monday 27th September 00 UTC showing colder air (green) pushing in across Ireland

Met Éireann meteorologist, Andrew Doran-Sherlock, said: “This weekend will see the last of the above average temperatures, with some places reaching around 20 degrees Celsius.  However, from Monday we’ll see a significant change with a much more autumnal feel to our weather, as temperatures dip to a cooler 12 to 15°Celsius.”

“Along with lower temperatures, it’ll turn quite unsettled too with spells of rain and heavy showers along with some windy conditions, which current indications suggest will persist through much of next week.”

Met Éireann are encouraging people to keep a close eye on the forecast this weekend and into next week as spells of heavy rain and showers could lead to hazardous weather conditions in some areas, with the potential for some localised flooding and tricky driving conditions.

Why the change in weather?

Currently the jet stream – the core of strong winds that lies over the boundary between the warmer air to the south and the colder air to the north – is lying to the north of Ireland.  As a deep depression develops in the mid-Atlantic later this weekend, the jet stream will wrap around the south of the depression, allowing colder air to sink down from the north over Ireland.

Andrew continued: “The change in weather from next week will be quite noticeable given conditions have been rather warm and settled so far this month – it may be time to dig out the autumn layers, hats and scarves as it is going to feel much chillier.”

Whatever the weather please follow the public health advice and help keep everybody safe from COVID-19.

For the most accurate and up to date 7-day, hourly forecast for your local area on the Island of Ireland go to The latest weather advisories and warnings for Ireland are on the Met Éireann Warnings page. These services and more are available on our free app – available from the App store for iPhone, and Play store for Android. Follow us on Twitter and Facebook for extra weather and climate content.