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 TUESDAY 09 DECEMBER 2025
Week 1 (Monday 15 December to Sunday 21 December)
It looks set to be an unsettled period with Low Pressure dominating Ireland’s weather bringing wet and windy weather at times. Rainfall totals are forecast to be well above normal across the country. Mean air temperatures are likely to be above the climatological average.
Week 2 (Monday 22 December to Sunday 28 December)
At forecast Week 2 and towards the latter part of December, the weather over Ireland is forecast to be mixed. The very unsettled weather of the preceding week is likely to give way to more changeable conditions with dry periods interspersed with wetter spells. Rainfall totals during the week are forecast to be around the seasonal norm. Mean air temperatures are likely to trend near the climatological average.
Week 3 (Monday 29 December to Sunday 04 January)
The end of December and early days of January are likely to see more of an influence of High Pressure than in preceding weeks. Precipitation totals are forecast to be below the seasonal average. Mean air temperatures are likely to be trend around average.
Week 4 (Monday 05 January to Sunday 11 January)
There is little trend in the forecast at Week 4 with the equal likelihood of settled and unsettled weather. There is no signal in the temperature forecast with an equal likelihood of milder or colder conditions. Similarly there is no signal for any particular trend in precipitation totals.
Seasonal Outlook for January February March 2026 (JFM):
The signal from the C3S seasonal models for Ireland during the JFM period is for above average temperatures. Rainfall amounts are less certain with the potential for wetter than average conditions overall.
Mean temperatures during JFM are signalled to be above average overall. Temperatures during the period are likely to trend between 0.5 and 1.0°C above normal, with the signal increasing through the period. However, colder than average periods, where all winter hazards are possible, could still occur at times throughout JFM, especially early on in the period.
There is a signal for above average rainfall overall, especially in the north and west of Ireland. This signal increases through JFM with March indicating the highest likelihood of above average rainfall out of the three months. Generally, there is potential for wetter and drier spells within the three months of JFM.
The sea surface temperatures (SSTs) around Irish coasts and over the Atlantic are expected to continue slightly above average during JFM. SSTs are trending 0.2 to 0.5 degrees higher than normal off the west and north coasts, with a trend of 0.5 to 1.0 degrees higher than normal off the south and east coasts.