Donegal Weather in September
Donegal in September averages 17°C (63°F) during the day and 10°C (50°F) at night. Keep in mind that quite a bit of rainfall is expected this month.
Rainfall in Donegal in September
The climate data from previous years indicates about 22 days of rain, averaging 107 mm (4.2 in) for the month. This is a wet month with frequent and often heavy showers. Both the number of rain days and the total rainfall are high.
Temperature in Donegal in September
In September, Donegal gets moderate temperatures, with highs of 17°C (63°F). Nights cool to around 10°C (50°F). Temperatures can feel cooler in the morning and evening, so layering is often the best approach. At 10°C (50°F) overnight, it gets properly cold after dark. On the bright side, cold nights tend to make for excellent sleeping conditions.
Sunshine in Donegal in September
The area experiences a moderate amount of sunshine, with approximately 118 hours of sunlight expected. This means a decent mix of sun and overcast.Our weather planner can help you find worldwide destinations with pleasant weather during this period. July and August typically offer the best weather for Donegal.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Ireland, check out our Donegal's climate page.
Donegal Temperature in September
Min Temperature
10°C (50°F)
Max Temperature
17°C (63°F)
Chance of Rain
72%
Precipitation
107 mm (4.2 in)
Rainy days
22 days
Sunshine
118 hours *
Percentage Sunshine
*
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Donegal typically stay consistent throughout September, with daily highs averaging around 17°C (63°F). Nights are cool, with lows typically ranging from 9°C (48°F) to 11°C (52°F).
Average temperatures in September
Historical weather for Donegal in September
Browse day-by-day weather records for Donegal spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Donegal historical weather extremes in September
Based on weather observations in Donegal between 1976 and 2025, these are the recorded extremes during September.
- On September 7, 2023, temperatures climbed to 27°C (81°F), marking the warmest September day on record.
- The lowest daytime temperature in September was 10°C (50°F), recorded on September 26, 2024.
- Donegal registered its coldest September night on September 30, 1991, with temperatures dropping to 0°C (32°F).
Best Places in Ireland in September
Find out more about the weather in Ireland and which places have the best travel conditions in this month. See all of Ireland in September →
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What to Wear in Donegal in September
For Donegal in September, you'll want flexible clothing. It's wise to pack cotton shirts, comfortable shorts, and a pair of jeans for cooler evenings. A light sweater or jacket is useful for air-conditioned spaces (like buses) or unexpected cool moments. High rain levels are expected, so pack waterproof gear and an umbrella or poncho. Sunglasses could come in handy during the sunnier parts of your trip.What To Do in Donegal in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Ireland, check out our Donegal's climate page.
See the full Donegal climate overview or explore weather in Ireland.
