Portsmouth
September
Weather in Portsmouth for September 2025
Your guide to Portsmouth weather in September - trends and predictions
In general, the average temperature in Portsmouth at the beginning of September is 20.3 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 16.7 °C by the end of September.
The climate of Portsmouth in September is notably wet, with an average of 13 rainy days.
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17
Dry days
13
Rainy days
0
Snow days
20°/16°
Temperatures
26 km/h
Avg max wind
76 %
Avg humidity
Portsmouth in September average weather
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| Mon. | Tue. | Wed. | Thu. | Fri. | Sat. | Sun. |
|---|---|---|---|---|---|---|
| 1  20° | 2  20° | 3  20° | 4 20° | 5 19° | 6 21° | 7 22° |
| 8  21° | 9 21° | 10 22° | 11 18° | 12  17° | 13 17° | 14 17° |
| 15 18° | 16 20° | 17 19° | 18 21° | 19 20° | 20  19° | 21 18° |
| 22 17° | 23 16° | 24 18° | 25 17° | 26  17° | 27 16° | 28 16° |
| 29 16° | 30 17° |
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Temperatures trend during September in Portsmouth
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. | Light rain | 20° /16° | 9.2 mm | 5 | |
| 2 Sept. | Light rain shower | 20° /15° | 1.5 mm | 5 | |
| 3 Sept. | Sunny | 20° /15° | 1.7 mm | 5 | |
| 4 Sept. | Sunny | 20° /15° | 2 mm | 5 | |
| 5 Sept. | Sunny | 19° /15° | 7.8 mm | 5 | |
| 6 Sept. | Sunny | 21° /17° | 9.4 mm | 5 | |
| 7 Sept. | Sunny | 22° /17° | 0.5 mm | 6 | |
| 8 Sept. | Partly cloudy | 21° /17° | 3.2 mm | 5 | |
| 9 Sept. | Partly cloudy | 21° /16° | 0.5 mm | 5 | |
| 10 Sept. | Partly cloudy | 22° /15° | 1.6 mm | 6 | |
| 11 Sept. | Partly cloudy | 18° /13° | 0.1 mm | 5 | |
| 12 Sept. | Overcast | 17° /12° | 0.6 mm | 4 | |
| 13 Sept. | Overcast | 17° /11° | 0 mm | 5 | |
| 14 Sept. | Partly cloudy | 17° /12° | 0 mm | 5 | |
| 15 Sept. | Sunny | 18° /14° | 0 mm | 5 | |
| 16 Sept. | Partly cloudy | 20° /15° | 0 mm | 6 | |
| 17 Sept. | Light rain shower | 19° /14° | 3.5 mm | 5 | |
| 18 Sept. | Light rain shower | 21° /14° | 3.3 mm | 5 | |
| 19 Sept. | Light rain shower | 20° /15° | 1.6 mm | 5 | |
| 20 Sept. | Moderate or heavy rain shower | 19° /15° | 10.4 mm | 5 | |
| 21 Sept. | Light rain shower | 18° /14° | 6.1 mm | 4 | |
| 22 Sept. | Light rain shower | 17° /13° | 2.6 mm | 4 | |
| 23 Sept. | Patchy rain possible | 16° /12° | 1 mm | 4 | |
| 24 Sept. | Overcast | 18° /14° | 1.5 mm | 4 | |
| 25 Sept. | Overcast | 17° /14° | 4.6 mm | 4 | |
| 26 Sept. | Patchy light rain with thunder | 17° /14° | 9.9 mm | 4 | |
| 27 Sept. | Patchy rain possible | 16° /12° | 4 mm | 4 | |
| 28 Sept. | Patchy rain possible | 16° /11° | 0.2 mm | 4 | |
| 29 Sept. | Overcast | 16° /12° | 2.7 mm | 4 | |
| 30 Sept. | Partly cloudy | 17° /12° | 6.6 mm | 5 | |
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Important Notice
Our weather forecast for Portsmouth 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 Portsmouth forecast closer to your planned date for the most up-to-date weather information.
Portsmouth in September - FAQ
What are the expected maximum and minimum temperatures in Portsmouth during September?
During September, expect a variety of temperatures with highs around 20° and lows near 16°, suitable for diverse activities and preferences.
How much rainfall should be expected in Portsmouth during September?
Moderate rainfall is anticipated in Portsmouth during September, with a total of 61.5 mm spread over approximately 13 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Portsmouth during September?
The average wind speed in Portsmouth during September is 26 km/h, suggesting breezy to windy conditions, depending on your activities.
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