Monthly forecasts can at times provide an insight into weather patterns in the month 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. Monthly forecast explained.
MONTHLY FORECAST, ISSUED TUESDAY 24 SEPTEMBER 2021
Week 1 (Monday 27 September to Sunday 03 October)
A noticeably cooler and unsettled week ahead than recently with our weather dominated by low pressure to the north feeding in a polar maritime air mass. Temperatures will be below average over the week and rainfall amounts will be above average throughout the country, especially over the western half of the country. Blustery conditions are likely at times, rainfall warnings are possible and there is the chance of thunderstorm activity.
Week 2 (Monday 04 October to Sunday 10 October)
Becoming milder for Week 2 with a southwesterly airflow dominating due to high pressure to the south and low pressure to the northwest. Temperatures will likely be above average, especially in the east of the country. However, rain and showers are still likely and much of the country could see above average rainfall amounts but more average amounts in the east and northeast. Rainfall warnings couldn’t be ruled out.
Week 3 (Monday 11 October to Sunday 17 October)
Continuing warmer than average in Week 3 with high pressure to the south building up a bit closer to Ireland with the low pressure declining northwards with a southwesterly airflow still predominant. The west and northwest could see above average rainfall with drier than average conditions in the south and east. Lower risk of hazardous rainfall amounts than previously.
Week 4 (Monday 18 October to Sunday 24 October)
A less clear signal for Week 4 with a possible weak northeasterly airflow developing with low pressure to the northwest. Temperatures will likely be around average for the time of year and rainfall amounts will likely be below normal for much of the country though showers feeding in from the Irish Sea could see more normal amounts for eastern and northeastern coasts. No clear signal for hazardous conditions though fog could be a feature of the nights.