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 25 NOVEMBER 2025
Week 1 (Monday 01 December to Sunday 07 December)
During week 1, the first week of meteorological winter, low pressure will be dominant, bringing generally unsettled conditions. Atlantic fronts will spread across the country from the southwest with frequent spells of rain and showers. Rainfall amounts will be above average nationwide as a result. The southwesterly airflow will also bring a mild airmass across Ireland, with above average temperatures expected.
Week 2 (Monday 08 December to Sunday 14 December)
During week 2, it will remain unsettled with nearby low pressure maintaining a predominantly southwesterly airflow over Ireland. Further spells of rain and showers are likely as a result with slightly above average rainfall across the country. Mean temperatures will stay higher than average nationwide also.
Week 3 (Monday 15 December to Sunday 21 December)
While confidence decreases in week 3, it is likely that a predominantly southerly airflow will lie across Ireland with low pressure across the Atlantic and high pressure across Europe. Rainfall amounts will decrease close to average across most of the country as high pressure has more of an influence, but rainfall amounts will be slightly above average in western and southwestern areas. Temperatures will remain slightly above normal.
Week 4 (Monday 22 December to Sunday 28 December)
While confidence is low in week 4, current indications suggest that Ireland will remain in a southerly airflow with occasional rain and showers, but some dry spells also. Rainfall amounts will be approximately normal as a result. Temperatures will be slightly above average for most areas.
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.