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 19 DECEMBER 2025
Week 1 (Monday 22 December to Sunday 28 December)
Strong signal for high pressure to be centred to the north of the UK and Ireland and become increasingly dominant through the period. Likely becoming mainly dry and settled in a mainly easterly airflow with temperatures below average, especially over southern and western parts. Potential hazards look limited to frost and fog patches, which could be persistent in sheltered spots.
Week 2 (Monday 29 December to Sunday 04 January)
Medium signal that high pressure will continue to dominate our weather into the new year, although centred to the northwest of Ireland, so creating a more northeasterly airflow over the country. Mainly dry conditions look set to continue with below average temperatures countrywide. Potential hazards look limited to frost, ice and fog; however, a few wintry showers can’t be ruled out at this stage. These would most likely occur near eastern and northern coasts.
Week 3 (Monday 05 January to Sunday 11 January)
Uncertainty increases quite dramatically by week 3, with no strong signal indicated. A more changeable period of weather seems like a reasonable assumption. There is a slight signal for drier than average conditions to continue in the west, but the signal for colder than average temperatures is diminished, with near average temperatures signalled overall.
Week 4 (Monday 12 January to Sunday 18 January)
Increased uncertainty continues into week 4, although there is a slight signal for high pressure to the northwest of Ireland to become dominant once again. Drier than average conditions are signalled across much of the country with closer to average precipitation signalled in the southeast and along the east coast. Mean temperatures are signalled to be near average overall.
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.