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September Weather in Dumbarton, United States

Last updated: June 24, 2025

In Dumbarton, United States, the average temperature in September hovers around 23°C (74°F). This month can see a minimum temperature of 8°C (47°F) and a maximum of 37°C (99°F), showcasing a wide range of warmth. Expect 97 mm (3.8 in) of precipitation spread over about 10 days, contributing to an average humidity of 75%. Stay prepared for the varied weather conditions!

September Temperature in Dumbarton

In September in Dumbarton, the average temperature is 23°C (74°F), with maximums reaching 37°C (99°F) and minimums dropping as low as 8°C (47°F). This makes it an ideal time to pack both light clothing for the warm days and a jacket for the cooler evenings, ensuring a comfortable and enjoyable trip.

September Weather in Dumbarton: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Dumbarton, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Dumbarton, September typically has an average temperature of 23°C (74°F), with highs reaching up to 37°C (99°F) and lows dropping to around 8°C (47°F).
JanFebMarAprMayJunJulAugSepOctNovDec404550606976817873645044
Data source: Temperature data for Dumbarton generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Dumbarton

In Dumbarton in September, the total precipitation amount is 97 mm (3.8 in) over a span of 10 days.

September Precipitation Trends in Dumbarton

The chart displays monthly precipitation patterns in Dumbarton, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Dumbarton, September typically receives around 97 mm (3.8 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec689972105102123105170971277495
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Dumbarton

In Dumbarton in September, humidity is 75%. With an average temperature of 23°C (74°F), this humidity feels like a warm, heavy blanket wrapping around you, making it feel more sweltering than it actually is, which can be quite uncomfortable for traveling.

September Average Humidity in Dumbarton

This chart illustrates the average monthly humidity levels in Dumbarton, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Dumbarton is approximately 75%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%84%84%82%83%83%79%77%75%81%87%85%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Dumbarton

In Dumbarton in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Dumbarton.

Maximum UV Index Levels in Dumbarton for September

The chart shows the monthly maximum UV Index (UVI) for Dumbarton in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Dumbarton typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3679101010109753
Data source: Dumbarton September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Dumbarton Compares to Other Months

Weather in Dumbarton varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Dumbarton, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Dumbarton, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather5°C (41°F)68 mm (2.7 inches)84%moderate
February Weather7°C (45°F)99 mm (3.9 inches)84%high
March Weather10°C (50°F)72 mm (2.8 inches)84%high
April Weather15°C (60°F)105 mm (4.1 inches)82%very high
May Weather20°C (69°F)102 mm (4.0 inches)82%very high
June Weather24°C (76°F)123 mm (4.9 inches)83%very high
July Weather27°C (81°F)104 mm (4.1 inches)79%very high
August Weather26°C (78°F)170 mm (6.7 inches)77%very high
September Weather23°C (74°F)97 mm (3.8 inches)75%very high
October Weather18°C (64°F)127 mm (5.0 inches)81%high
November Weather10°C (50°F)74 mm (2.9 inches)87%moderate
December Weather7°C (44°F)95 mm (3.7 inches)85%moderate

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