Northern Ireland (Belfast)
September
Weather in Northern Ireland for September 2025
Your guide to Northern Ireland weather in September - trends and predictions
In general, the average temperature in Northern Ireland at the beginning of September is 18.6 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 13.3 °C by the end of September.
Expect significant rainfall in Northern Ireland during September, with an average of 19 rainy days.
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11
Dry days
19
Rainy days
0
Snow days
16°/10°
Temperatures
24 km/h
Avg max wind
87 %
Avg humidity
Northern Ireland in September average weather
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| Mon. | Tue. | Wed. | Thu. | Fri. | Sat. | Sun. |
|---|---|---|---|---|---|---|
| 1  16° | 2 18° | 3  18° | 4 17° | 5  19° | 6 21° | 7 21° |
| 8 21° | 9 19° | 10  17° | 11 14° | 12 14° | 13  14° | 14 16° |
| 15  13° | 16  16° | 17  17° | 18 15° | 19 17° | 20 17° | 21 15° |
| 22 15° | 23 14° | 24 15° | 25 13° | 26 12° | 27 13° | 28 14° |
| 29 14° | 30 12° |
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Temperatures trend during September in Northern Ireland
See the weather trend as well as the moving average line
September weather day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| 1 Sept. | Patchy rain possible | 16° /11° | 0.7 mm | 4 | |
| 2 Sept. | Patchy rain possible | 18° /10° | 4.7 mm | 4 | |
| 3 Sept. | Sunny | 18° /9° | 0.3 mm | 5 | |
| 4 Sept. | Sunny | 17° /9° | 0.9 mm | 5 | |
| 5 Sept. | Partly cloudy | 19° /10° | 0 mm | 5 | |
| 6 Sept. | Partly cloudy | 21° /12° | 0 mm | 6 | |
| 7 Sept. | Patchy rain possible | 21° /12° | 1.2 mm | 5 | |
| 8 Sept. | Partly cloudy | 21° /11° | 0.9 mm | 5 | |
| 9 Sept. | Patchy rain possible | 19° /11° | 0.7 mm | 5 | |
| 10 Sept. | Moderate or heavy rain shower | 17° /10° | 8.1 mm | 4 | |
| 11 Sept. | Light rain shower | 14° /8° | 4.1 mm | 4 | |
| 12 Sept. | Partly cloudy | 14° /5° | 0.6 mm | 4 | |
| 13 Sept. | Overcast | 14° /5° | 0.6 mm | 4 | |
| 14 Sept. | Overcast | 16° /9° | 0.2 mm | 4 | |
| 15 Sept. | Moderate rain | 13° /8° | 9.2 mm | 4 | |
| 16 Sept. | Cloudy | 16° /7° | 0 mm | 4 | |
| 17 Sept. | Light rain | 17° /10° | 8.4 mm | 4 | |
| 18 Sept. | Patchy rain possible | 15° /9° | 2.2 mm | 4 | |
| 19 Sept. | Light rain | 17° /9° | 4.1 mm | 4 | |
| 20 Sept. | Light rain shower | 17° /9° | 2.3 mm | 4 | |
| 21 Sept. | Light rain shower | 15° /7° | 0.7 mm | 4 | |
| 22 Sept. | Light rain shower | 15° /8° | 1.6 mm | 4 | |
| 23 Sept. | Light drizzle | 14° /6° | 0.6 mm | 4 | |
| 24 Sept. | Light rain shower | 15° /10° | 7.4 mm | 4 | |
| 25 Sept. | Patchy rain possible | 13° /9° | 1.9 mm | 4 | |
| 26 Sept. | Light rain shower | 12° /7° | 14.5 mm | 3 | |
| 27 Sept. | Light rain shower | 13° /6° | 10.6 mm | 3 | |
| 28 Sept. | Light rain shower | 14° /6° | 2.1 mm | 4 | |
| 29 Sept. | Patchy rain possible | 14° /7° | 1 mm | 4 | |
| 30 Sept. | Light rain shower | 12° /8° | 12.2 mm | 3 | |
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Important Notice
Our weather forecast for Northern Ireland 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 Northern Ireland forecast closer to your planned date for the most up-to-date weather information.
Northern Ireland in September - FAQ
What are the expected maximum and minimum temperatures in Northern Ireland during September?
Enjoy moderate daytime temperatures of up to 16° and cooler nights around 10°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Northern Ireland during September?
Significant rainfall exceeding 128.1 mm is expected in Northern Ireland during September, occurring over more than 19 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Northern Ireland during September?
The average wind speed in Northern Ireland during September is 24 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Northern Ireland
Explore the daily rainfall trends and prepare for Northern Irelands September weather 💧
UV exposure in Northern Ireland during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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