The extended range forecast, which includes the monthly and seasonal forecasts, can at times provide an insight into weather patterns in the months ahead. However, they should not be used for specific planning purposes as they have generally low skill compared with the 10-day forecast. This is because forecasts beyond one week become increasingly uncertain due to the chaotic nature of the atmosphere. Further information can be found here Monthly and seasonal forecast explained.
Images: Shutterstock/gabriel12. Met Éireann HQ during Storm Emma 2018
MONTHLY FORECAST, ISSUED FRIDAY 13 DECEMBER 2024
Week 1 (Monday 16 December to Sunday 22 December)
A changeable weather pattern is forecast in the week leading up to Christmas. A fairly mobile, predominantly westerly air-flow will be established over Ireland. There will be alternating periods of cold and mild weather but overall mean air temperatures are forecast to trend slightly above the climatological average. Rainfall totals are forecast to vary across the country with western and northern areas seeing above normal precipitation totals and eastern and southern counties below normal rainfall amounts.
Week 2 (Monday 23 December to Sunday 29 December)
Current indications suggest the weather will settle down for the final week of December with high pressure the dominant feature. Rainfall totals are forecast to be below the December average across the country. Mean air temperatures are forecast to trend slightly above the monthly norm.
Week 3 (Monday 30 December to Sunday 05 January)
Early indications suggest High Pressure will retreat into the Atlantic into the first week of January 2025 bringing more changeable weather conditions over Ireland. Precipitation amounts are forecast to be generally below normal but may trend above normal across northern counties. Mean air temperatures are currently projected to trend slightly above normal.
Week 4 (Monday 06 January to Sunday 12 January)
At Forecast Week 4, there are only weak trends in the forecast data. High pressure may be slightly more prevalent than usual bringing somewhat more settled weather than the climatological mean. Mean air temperatures and rainfall totals are forecast to be close to the January norm.
Seasonal Outlook for January, February and March 2025 (JFM)
The signal from the C3S seasonal models for Ireland during the JFM period is for above average temperatures. Rainfall amounts are less certain but there is a signal for wetter than average spells of weather, particularly in January.
Mean temperatures during JFM are signalled to be above average overall. Temperatures during January are likely to trend between 1.0 and 2.0°C above average, while temperatures in February and March are likely to be between 0.5 and 1.0°C above normal.
The rainfall forecast is less certain but there is potential for wetter than average conditions across the three months, especially in January and in the north and west of the country.
The sea surface temperatures around Irish coasts and over the Atlantic are expected to be above average during JFM, trending 0.2 to 1.0°C degrees higher than normal generally. Sea surface temperatures are expected to be closest to normal near north and northwest coasts.