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September Weather in Derby Line, United States

Last updated: June 24, 2025

In September, the average temperature in Derby Line, United States hovers around 14°C (58°F), with potential extremes ranging from a chilly -4°C (26°F) to a warm 29°C (85°F). Expect about 83 mm (3.3 in) of precipitation over 9 days, contributing to an average humidity of 77%. Prepare for a mix of cool breezes and occasional rainfall!

September Temperature in Derby Line

In September in Derby Line, the average temperature is 14°C (58°F). Maximums can reach 29°C (85°F), while minimums can drop as low as -4°C (26°F). This variation makes it advisable to pack layers and be prepared for both warm and chilly weather while traveling.

September Weather in Derby Line: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Derby Line, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Derby Line, September typically has an average temperature of 14°C (58°F), with highs reaching up to 29°C (85°F) and lows dropping to around -4°C (26°F).
JanFebMarAprMayJunJulAugSepOctNovDec171927405362676658473222
Data source: Temperature data for Derby Line 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 Derby Line

In Derby Line in September, the precipitation amount is 83 mm (3.3 in) over the course of 9 days.

September Precipitation Trends in Derby Line

The chart displays monthly precipitation patterns in Derby Line, 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 Derby Line, September typically receives around 83 mm (3.3 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec8882801121031161191048314911484
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Derby Line

In Derby Line in September, humidity is 77%. With an average temperature of 14°C (58°F), this humidity feels like a warm blanket wrapping around you, making traveling feel sticky and heavy, yet still manageable as you explore the sights.

September Average Humidity in Derby Line

This chart illustrates the average monthly humidity levels in Derby Line, 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 Derby Line is approximately 77%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec91%89%85%84%78%72%75%74%77%85%86%85%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Derby Line

In Derby Line in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Derby Line.

Maximum UV Index Levels in Derby Line for September

The chart shows the monthly maximum UV Index (UVI) for Derby Line 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 Derby Line typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec245799987532
Data source: Derby Line 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 Derby Line Compares to Other Months

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

This table compares monthly weather conditions in Derby Line, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-8°C (17°F)88 mm (3.5 inches)91%low
February Weather-7°C (20°F)82 mm (3.2 inches)89%moderate
March Weather-3°C (27°F)80 mm (3.1 inches)85%moderate
April Weather5°C (40°F)112 mm (4.4 inches)84%high
May Weather12°C (53°F)103 mm (4.1 inches)78%very high
June Weather17°C (62°F)116 mm (4.5 inches)72%very high
July Weather20°C (67°F)119 mm (4.7 inches)75%very high
August Weather19°C (66°F)104 mm (4.1 inches)74%very high
September Weather14°C (58°F)83 mm (3.3 inches)77%high
October Weather8°C (47°F)149 mm (5.9 inches)85%moderate
November Weather0°C (33°F)114 mm (4.5 inches)86%moderate
December Weather-5°C (23°F)84 mm (3.3 inches)85%low

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