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 14 NOVEMBER 2025
Week 1 (Monday 17 November to Sunday 23 November)
Atlantic ridging is strongly signalled during this period, with high pressure signalled to be centred to the west and northwest of Ireland, with lower pressure over Scandinavia and northern parts of the European continent. This synoptic set-up favours a generally northerly airflow over Ireland and unsurprisingly, a colder than average temperature anomaly is signalled for the period. Generally drier than average conditions are also signalled, however there is a chance of near to slightly wetter than average conditions near the east coast for the period.
Week 2 (Monday 24 November to Sunday 30 November)
Low confidence in the details through this period but mixed conditions are signalled in general. There are hints that there will be some level of Atlantic mobility, indicating frontal passages, during the period as lower pressure is signalled to be slightly more pronounced over northern and western parts of Europe with comparatively higher pressure signalled over southern parts. Predictably, slightly higher than average temperatures and rainfall are signalled for this period.
Week 3 (Monday 01 December to Sunday 07 December)
There appears to be a trend towards more blocked conditions for this period with higher than average pressure anomalies signalled over Scandinavia and northwestern parts of the Europe. The precipitation anomaly for this period is mixed with some northwestern areas signalled to have drier that average conditions while southern counties may experience slightly wetter than average conditions. Many other parts look likely to have near normal rainfall amounts. Temperatures are generally signalled to be slightly above normal.
Week 4 (Monday 08 December to Sunday 14 December)
As to be expected, confidence is reduced for this time period. There’s a weak signal for a slowly evolving transition from blocked flow to something a bit more mobile. Slightly wetter than average conditions for the south and east, with drier conditions in the west and north. Temperatures near to slightly above average for December.
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.