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 December January February 2025-26 (DJF):
The signal from the C3S seasonal models for Ireland during the DJF period is for above average temperatures. Rainfall amounts are less certain with the potential for slightly wetter than average conditions overall, with both wetter and drier periods possible within the three months.
Mean temperatures during DJF are signalled to be above average overall. Temperatures during the period are likely to trend between 0.5 and 1.0°C above normal. However, there is a higher likelihood of cold spells occurring compared to recent winters, with all winter hazards possible, throughout DJF, especially in December.
The rainfall forecast is less certain. There is a slight signal for above average rainfall overall, especially in the north and northwest of Ireland. Generally, there is potential for wetter and drier spells within the three months of DJF.
The sea surface temperatures (SSTs) around Irish coasts and over the Atlantic are expected to continue slightly above average during DJF. SSTs are trending 0.5 to 1.0 degrees higher than normal generally, with a trend of 0.2 to 0.5 degrees higher than normal off northern coasts.