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 02 DECEMBER 2025
Week 1 (Monday 08 December to Sunday 14 December)
Atlantic low pressure is strongly signalled for next week. Predictably with this set up, precipitation and mean temperatures are signalled to be above average, although this does not preclude some chilly nights. With low pressure dominating, there is potential for wind and rain warnings during this period.
Week 2 (Monday 15 December to Sunday 21 December)
Atlantic low pressure remains the dominant signal into week 2, although it is a weaker signal when compared to week 1. Once again, precipitation and mean temperatures are forecast to be above average overall.
Week 3 (Monday 22 December to Sunday 28 December)
The signal for Atlantic low pressure persists into week 3, though the signal is much more diffuse compared to previous weeks which may indicate a transitional period or regime change. Precipitation is weakly signalled to be above average across the south and east, while near normal or drier than average conditions are signalled in the west and northwest. Mean temperatures are signalled to trend near to above normal.
Week 4 (Monday 29 December to Sunday 04 January)
Confidence is very low for this period. High pressure is signalled over central and southern parts of the European continent, with lower pressure anomalies in the Atlantic. This would indicate an overall mild southwesterly airflow. Mean temperatures are signalled to be above average as is precipitation.
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.