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 16 SEPTEMBER 2025
Week 1 (Monday 22 September to Sunday 28 September)
Week 1 is indicating rather unsettled conditions. The overall signal is for low pressure to to the southwest of Ireland to be the dominant force resulting in wetter than average conditions across much of the country. Mean air temperatures will likely be close to or slightly below normal for the time of year.
Week 2 (Monday 29 September to Sunday 05 October)
While confidence in week 2 is lower, there is little change indicated in week 2. Low pressure looks to continue to dominate conditions with the precipitation anomaly indicating wetter than average conditions this week. Mean air temperatures are likely to be around normal for the time of year.
Week 3 (Monday 06 October to Sunday 12 October)
There is increasing uncertainty in the forecast for week 3. There is no signal for either high or low pressure to dominate our weather this week. Overall there is a signal more settled conditions this week as the precipitation anomaly indicates for drier than average conditions while mean air temperatures will remain around average this week.
Week 4 (Monday 13 October to Sunday 19 October)
In week 4 the forecast confidence is low. There is a slight signal for low pressure to the north of Ireland potentially bringing more mixed conditions this week. There is a signal for rainfall amounts along the west and north coasts to be wetter than average while the east coast signals drier than average conditions for week 4. Again, mean air temperatures will likely continue around average for the time of year.
Seasonal Outlook for October November December 2025 (OND)
The signal from the C3S seasonal models for Ireland during the OND period is for above average temperatures.Rainfall amounts are less certain with the possibility of precipitation trending near average overall.
Mean temperatures during OND 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, colder than average periods, where winter hazards are possible, could still occur at times towards the end of OND.
The rainfall forecast is less certain. There is a slight signal for above average rainfall during October and a trend towards below average rainfall for November.Meanwhile, the signal for December is more mixed with the potential for both wetter and drier spells.
The sea surface temperatures (SSTs) around Irish coasts are expected to continue slightly above average during OND.