September weather forecast and climate
Dublin, Ireland

A sunset view of the illuminated Ha Penny Bridge reflected in the water below, found in Dublin, Ireland
A sunset view of the illuminated Ha Penny Bridge reflected in the water below, found in Dublin, Ireland
September is the arrival of autumn with temperatures in a mildly cold range of 9.4°C (48.9°F) to 16.7°C (62.1°F). It is another great month for swimming with bearable water temperatures and water activities such as the Dublin City Liffey Swim.
Rain is in the form of intermittent drizzling as September has the least number of monthly rainy days.
Lovely fall weather is a beautiful time to explore the ocean with many cruises and ferries engaged in local daylong excursions.
Average temperature in September - Dublin, Ireland
  • Average high temperature in September: 17.3°C

The warmest month (with the highest average high temperature) is July (20.2°C).
The month with the lowest average high temperature is January (8.8°C).

  • Average low temperature in September: 11.4°C

The month with the highest average low temperature is July (13.5°C).
Coldest months (with the lowest average low temperature) are January and February (3.9°C).

Average rainfall in September - Dublin, Ireland
  • Average rainfall in September: 56.7mm

The wettest month (with the highest rainfall) is October (76mm).
The driest month (with the lowest rainfall) is February (46.1mm).

Average rainfall days in September - Dublin, Ireland
  • Average rainfall days in September: 9 days

Months with the highest number of rainy days are January, October and December (12 days).
Months with the lowest number of rainy days are June and September (9 days).

Average sea temperature in September - Dublin, Ireland
  • Average sea temperature in September: 14.8°C

The best month for swimming (with the highest average sea temperature) is August (14.9°C).
The coldest month (with the lowest average sea temperature) is March (8.4°C).

Average daylight in September / Average sunshine in September - Dublin, Ireland
  • Average daylight in September: 12.7h

The month with the longest days is June (Average daylight: 16.9h).
The month with shortest days is December (Average daylight: 7.6h).

  • Average sunshine in September: 4.3h

The month with most sunshine is May (Average sunshine: 6.3h).
The month with least sunshine is December (Average sunshine: 1.7h).

Average UV index in September - Dublin, Ireland
  • Average UV index in September: 4

Months with the highest UV index are June and July (UV index 6).
Months with the lowest UV index are January and December (UV index 0).

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