Ulster (Donegal)
September
Weather in Ulster for September 2025
Your guide to Ulster weather in September - trends and predictions
Until now, September 2025 in Ulster is cooler than usual, with temperatures averaging 14.5 °C, this is -2.2 °C below the typical seasonal average.
Expect cooler weather in the next days in Ulster with the forecast suggesting a temperature of 13.7 °C, lower than the historical average.
In general, the average temperature in Ulster at the beginning of September is 18.6 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 13.6 °C by the end of September.
Ulster experiences heavy rainfall in September, with over 20 rainy days and an average total precipitation 104.1 mm.
Temperatures
Rain 🌧️
4
Dry days
26
Rainy days
0
Snow days
16°/8°
Temperatures
19 km/h
Avg max wind
83 %
Avg humidity
Ulster Weather September
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What’s the Weather Like in Ulster This September?
Discover the average temperatures and weather trends across Ulster’s cities this September.
Temperatures trend during September in Ulster
See the weather trend as well as the moving average line
September weather in Ulster day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| 1 Sept. |  Light rain shower | 17° /9° | 6.8 mm | 4 | |
| 2 Sept. | Light rain shower | 17° /9° | 3.5 mm | 4 | |
| 3 Sept. |  Sunny | 17° /9° | 1.4 mm | 4 | |
| 4 Sept. |  Partly cloudy | 18° /8° | 0.8 mm | 4 | |
| 5 Sept. |  Mist | 19° /9° | 0.2 mm | 4 | |
| 6 Sept. | Light rain shower | 21° /11° | 1.4 mm | 5 | |
| 7 Sept. | Partly cloudy | 21° /11° | 1.9 mm | 5 | |
| 8 Sept. | Light rain shower | 18° /10° | 3.2 mm | 4 | |
| 9 Sept. | Light rain shower | 16° /10° | 2 mm | 4 | |
| 10 Sept. | Mist | 15° /10° | 8.4 mm | 4 | |
| 11 Sept. | Light rain shower | 13° /8° | 8 mm | 3 | |
| 12 Sept. | Light rain shower | 13° /6° | 5.3 mm | 3 | |
| 13 Sept. |  Moderate rain | 12° /5° | 10 mm | 3 | |
| 14 Sept. |  Overcast | 14° /8° | 3.9 mm | 3 | |
| 15 Sept. | Moderate rain | 15° /11° | 12.5 mm | 0.5 | |
| 16 Sept. | Patchy rain possible | 15° /10° | 4.5 mm | 0.8 | |
| 17 Sept. | Moderate rain | 16° /10° | 10.2 mm | 0.7 | |
| 18 Sept. | Moderate rain | 16° /11° | 10 mm | 0.7 | |
| 19 Sept. | Patchy rain possible | 15° /10° | 2.6 mm | 0.6 | |
| 20 Sept. | Patchy rain possible | 10° /9° | 0.2 mm | 2 | |
| 21 Sept. | Patchy rain possible | 9° /7° | 4 mm | 2 | |
| 22 Sept. | Patchy rain possible | 13° /9° | 0.1 mm | 3 | |
| 23 Sept. | Patchy rain possible | 15° /9° | 0.5 mm | 3 | |
| 24 Sept. | Patchy rain possible | 13° /9° | 4.1 mm | 3 | |
| 25 Sept. | Patchy rain possible | 13° /10° | 0.7 mm | 3 | |
| 26 Sept. | Patchy rain possible | 15° /8° | 2.8 mm | 3 | |
| 27 Sept. | Patchy rain possible | 14° /10° | 2.5 mm | 3 | |
| 28 Sept. | Patchy rain possible | 13° /9° | 3.3 mm | 3 | |
| 29 Sept. | Light rain shower | 14° /7° | 1.5 mm | 3 | |
| 30 Sept. |  Light drizzle | 13° /7° | 2.9 mm | 3 | |
| Next | |||||
Important Notice
Our weather forecast for Ulster in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Ulster forecast closer to your planned date for the most up-to-date weather information.
Change Month
Ulster in September - FAQ
What are the expected maximum and minimum temperatures in Ulster during September?
Enjoy moderate daytime temperatures of up to 16° and cooler nights around 8°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Ulster during September?
Significant rainfall exceeding 104.1 mm is expected in Ulster during September, occurring over more than 26 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Ulster during September?
The average wind speed in Ulster during September is 19 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Ulster
Explore the daily rainfall trends and prepare for Ulsters September weather 💧
UV exposure in Ulster during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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