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 FRIDAY 17 SEPTEMBER 2021
Week 1 (Monday 20 September to Sunday 26 September)
Low pressure looks set to be the dominant theme over Ireland during this period with high pressure displaced to the east over Scandinavia. Outbreaks of rain or showers possible in all parts with above average rainfall indicated countrywide, but particularly so over the western half of the country. Temperature look likely to be near normal overall, slightly higher than average in the eastern half of the country and along the south coast. With low pressure in charge overall, the potential for rainfall and possible wind warnings is high. Current indications suggest high pressure will be in charge at the start of the period with temperatures generally above average, before trending towards low pressure and near to slightly below average temperatures later in the week.
Week 2 (Monday 27 September to Sunday 03 October)
Confidence is lower for week 2, but low pressure over Ireland is indicated. This would indicate outbreaks of rain or showers for most parts. Rainfall looks set to be above average again with temperatures close to normal overall. There is some potential for rainfall warnings.
Week 3 (Monday 04 October to Sunday 10 October)
Low confidence in the details for this period with only a slight tendency towards lower pressure over the northern half of the country, with more neutral conditions indicated to the south. Slightly wetter than normal conditions are indicated with average temperatures for the time of year.
Week 4 (Monday 11 October to Sunday 17 October)
Again, confidence in the forecast for this period remains low. The signal does lean more towards higher than average pressure, however. It follows that the rainfall indicator leans towards drier than normal conditions. Temperatures look likely to be near average overall.