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
Issued: 15/09/2026 14:00
Week 1 – Monday 21st September to Sunday 27th September
Current indications are for high pressure to become more dominant, bringing more settled conditions with below average rainfall amounts and above average temperatures.
Week 2 – Monday 28th September to Sunday 04th October
While the influence of high pressure is expected to wane, temperatures are still expected to remain above average with rainfall amounts average or slightly below
Week 3 – Monday 05th October to Sunday 11th October
With uncertainty increasing, there is neither a signal for high pressure nor low pressure to dominate. Mean air temperatures are expected to continue slightly above average, with slightly higher than average rainfall also expected.
Week 4 – Monday 12th October to Sunday 18th October
While confidence is low, there is a slight signal for low pressure to become dominant. Temperatures are expected to remain slightly above average, with average or slightly above rainfall amounts.
Seasonal Outlook for October, November, December (OND):
The signal from the C3S seasonal models for Ireland during the OND period is for above average temperatures. Rainfall amounts are also likely to trend above average with a strong signal for wet and unsettled conditions at times during OND.
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 for OND signals the potential for above average rainfall throughout the period, especially in the south. The highest likelihood for wetter than average conditions are signalled during November.
The sea surface temperatures (SSTs) around Irish coasts are expected to continue above average during OND, trending 0.2 to 1.0 degrees higher than normal generally.