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September Weather in Potomac, United States

Last updated: June 24, 2025

In Potomac, United States, the average temperature in September hovers around 21°C (70°F). However, be prepared for a temperature range that dips to a chilly 6°C (42°F) and soars to a scorching 34°C (93°F). During this month, expect about 76 mm (3.0 in) of precipitation spread over 7 days, and a high average humidity of 80%, contributing to a steamy atmosphere that defines this time of year.

September Temperature in Potomac

In September in Potomac, the average temperature is 21°C (70°F), with maximums reaching 34°C (93°F) and minimums dropping as low as 6°C (42°F). This pleasant climate makes Potomac an ideal destination for travelers seeking a comfortable getaway.

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

The chart illustrates September temperature patterns in Potomac, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Potomac, September typically has an average temperature of 21°C (70°F), with highs reaching up to 34°C (93°F) and lows dropping to around 6°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec283142526474777470574135
Data source: Temperature data for Potomac 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 Potomac

In Potomac in September, the precipitation amount is 76 mm (3.0 in) over a period of 7 days.

September Precipitation Trends in Potomac

The chart displays monthly precipitation patterns in Potomac, 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 Potomac, September typically receives around 76 mm (3.0 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec777711111814711287110761197459
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Potomac

In Potomac in September humidity is 80%. With an average temperature of 21°C (70°F), this humidity feels like a warm, enveloping blanket that can make even short walks feel draining, urging travelers to seek shade or a cool drink frequently.

September Average Humidity in Potomac

This chart illustrates the average monthly humidity levels in Potomac, 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 Potomac is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%83%84%85%79%82%80%81%80%82%88%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Potomac

In Potomac in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Potomac.

Maximum UV Index Levels in Potomac for September

The chart shows the monthly maximum UV Index (UVI) for Potomac 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 Potomac typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910111098642
Data source: Potomac 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 Potomac Compares to Other Months

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

This table compares monthly weather conditions in Potomac, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)77 mm (3.0 inches)82%moderate
February Weather-1°C (31°F)77 mm (3.0 inches)83%moderate
March Weather6°C (43°F)111 mm (4.4 inches)84%high
April Weather11°C (52°F)118 mm (4.6 inches)85%very high
May Weather18°C (65°F)147 mm (5.8 inches)79%very high
June Weather23°C (74°F)112 mm (4.4 inches)82%extreme
July Weather25°C (77°F)87 mm (3.4 inches)80%very high
August Weather23°C (74°F)110 mm (4.3 inches)81%very high
September Weather21°C (70°F)76 mm (3.0 inches)80%very high
October Weather14°C (57°F)119 mm (4.7 inches)82%high
November Weather5°C (41°F)74 mm (2.9 inches)88%moderate
December Weather2°C (36°F)59 mm (2.3 inches)84%low

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