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: 15/05/2026
Week 1 – Monday 18th May to Sunday 24th May
Currently, there is no clear signal for pressure over Ireland. There is a slight signal for low pressure to the west coast, with a weaker signal for higher pressure to the southeast. Temperatures are expected to be slightly above average for week 1. Precipitation anomaly is also signalling higher than average amounts.
Week 2 – Monday 25th May to Sunday 31st May
Going into week 2, there is a signal for higher pressure to influence our weather pattern. Temperatures are expected to remain above average throughout the period, while precipitation amounts are expected to be below average.
Week 3 – Monday 01st June to Sunday 07th June
In week 3, confidence decreases. While there is no clear indication of pressure, there is a slight signal for higher pressure to the Southwest of Ireland. A higher than average temperature anomaly remains to the eastern half of the country. No clear signal is indicated for precipitation amounts, with a slight signal for lower than average amounts to the Southwest, whereas a higher than average signal is noted to the northwest.
Week 4 – Monday 08th June to Sunday 14th June
In week 4, uncertainty in the forecast continues to decrease. While there is no signal for influencing pressure weather, it does look like conditions will remain drier or average for this time of year. Temperatures follow a similar pattern, with the exception of the far east, where a slight signal for warmer than average temperatures is shown.
Seasonal Outlook for June July August 2026 (JJA):
The signal from the C3S seasonal models for Ireland during the JJA period is for above average temperatures. Rainfall is likely to be below average during the period.
Mean temperatures during JJA are signalled to be above average overall. Temperatures are likely to trend between 0.2 and 1.0°C above average generally. The likelihood of higher than normal temperatures is strongest in August.
The rainfall forecast is less certain, with a weak signal for below average rainfall overall, especially during June and August.
The sea surface temperatures around Irish coasts are expected to continue slightly above average during JJA, trending 0.2 to 0.5°C degrees higher than normal generally.