Mercer County (Princeton)
September
Weather in Mercer County for September 2025
Your guide to Mercer County weather in September - trends and predictions
In general, the average temperature in Mercer County at the beginning of September is 24 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 19.9 °F by the end of September.
Mercer County experiences moderate rainfall in September, with an average of 10 rainy days and a total precipitation of 80.2 mm.
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Temperatures
Rain 🌧️
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20
Dry days
10
Rainy days
0
Snow days
23°/15°
Temperatures
16 km/h
Avg max wind
72 %
Avg humidity
Mercer County in September average weather
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| Mon. | Tue. | Wed. | Thu. | Fri. | Sat. | Sun. |
|---|---|---|---|---|---|---|
| 1  27° | 2  25° | 3  23° | 4 24° | 5 25° | 6 22° | 7 22° |
| 8 21° | 9 24° | 10 26° | 11 26° | 12 27° | 13 28° | 14 28° |
| 15 27° | 16 25° | 17  20° | 18 20° | 19  23° | 20  20° | 21 23° |
| 22  21° | 23 19° | 24 18° | 25 19° | 26 25° | 27 21° | 28 20° |
| 29  17° | 30 19° |
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Temperatures trend during September in Mercer County
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 |
|---|---|---|---|---|---|
| Sept. 1 | Light rain shower | 27° /20° | 3.1 mm | 6 | |
| Sept. 2 | Partly cloudy | 25° /15° | 0 mm | 6 | |
| Sept. 3 | Sunny | 23° /11° | 0 mm | 6 | |
| Sept. 4 | Partly cloudy | 24° /12° | 0 mm | 6 | |
| Sept. 5 | Sunny | 25° /13° | 0 mm | 6 | |
| Sept. 6 | Patchy rain possible | 22° /16° | 0.1 mm | 5 | |
| Sept. 7 | Light rain shower | 22° /12° | 5.8 mm | 5 | |
| Sept. 8 | Sunny | 21° /9° | 0 mm | 6 | |
| Sept. 9 | Sunny | 24° /10° | 0 mm | 6 | |
| Sept. 10 | Sunny | 26° /14° | 0 mm | 7 | |
| Sept. 11 | Partly cloudy | 26° /13° | 0 mm | 7 | |
| Sept. 12 | Sunny | 27° /14° | 0 mm | 7 | |
| Sept. 13 | Sunny | 28° /14° | 0 mm | 7 | |
| Sept. 14 | Sunny | 28° /16° | 0 mm | 7 | |
| Sept. 15 | Sunny | 27° /16° | 0 mm | 7 | |
| Sept. 16 | Partly cloudy | 25° /15° | 0 mm | 6 | |
| Sept. 17 | Fog | 20° /17° | 0 mm | 5 | |
| Sept. 18 | Fog | 20° /17° | 0 mm | 5 | |
| Sept. 19 | Overcast | 23° /18° | 12.3 mm | 5 | |
| Sept. 20 | Moderate or heavy rain shower | 20° /17° | 9.8 mm | 5 | |
| Sept. 21 | Overcast | 23° /18° | 0 mm | 5 | |
| Sept. 22 | Cloudy | 21° /14° | 0 mm | 5 | |
| Sept. 23 | Overcast | 19° /14° | 0 mm | 4 | |
| Sept. 24 | Overcast | 18° /16° | 2.4 mm | 4 | |
| Sept. 25 | Moderate or heavy rain shower | 19° /16° | 20.5 mm | 4 | |
| Sept. 26 | Overcast | 25° /19° | 7.1 mm | 6 | |
| Sept. 27 | Fog | 21° /18° | 5.4 mm | 5 | |
| Sept. 28 | Overcast | 20° /17° | 3.5 mm | 5 | |
| Sept. 29 | Light rain | 17° /15° | 10 mm | 4 | |
| Sept. 30 | Overcast | 19° /15° | 0 mm | 4 | |
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Important Notice
Our weather forecast for Mercer County 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 Mercer County forecast closer to your planned date for the most up-to-date weather information.
Mercer County in September - FAQ
What are the expected maximum and minimum temperatures in Mercer County during September?
During September, expect a variety of temperatures with highs around 23° and lows near 15°, suitable for diverse activities and preferences.
How much rainfall should be expected in Mercer County during September?
Moderate rainfall is anticipated in Mercer County during September, with a total of 80.2 mm spread over approximately 10 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Mercer County during September?
The average wind speed in Mercer County during September is 16 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Mercer County
Explore the daily rainfall trends and prepare for Mercer Countys September weather 💧
UV exposure in Mercer County during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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Where is Mercer County?Get accurate weather forecasts for Mercer County, located at latitude 40.349 and longitude -74.659. Stay updated with localized weather information tailored for Mercer County.
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