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September Weather in Arlington, United States

Last updated: June 24, 2025

In September, the average temperature in Arlington, United States is a comfortable 20°C (68°F). Expect temperatures to vary, with a minimum of 4°C (40°F) and highs reaching up to 33°C (92°F). You might encounter moderate rainfall, with 70 mm (2.7 in) of precipitation spread over approximately 9 days. The average humidity during this month sits at a notable 78%, making it a season of both warmth and occasional moisture.

September Temperature in Arlington

In September, in Arlington, the average temperature is 20°C (68°F). Maximums can reach 33°C (92°F), and minimums can be as low as 4°C (40°F). It's advisable to pack layers to accommodate both warm days and cooler nights while enjoying your travels.

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

The chart illustrates September temperature patterns in Arlington, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Arlington, September typically has an average temperature of 20°C (68°F), with highs reaching up to 33°C (92°F) and lows dropping to around 4°C (40°F).
JanFebMarAprMayJunJulAugSepOctNovDec293141506272757368574135
Data source: Temperature data for Arlington 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 Arlington

In Arlington in September, the precipitation amount is 70 mm (2.7 in) over the course of 9 days.

September Precipitation Trends in Arlington

The chart displays monthly precipitation patterns in Arlington, 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 Arlington, September typically receives around 70 mm (2.7 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec7285951031361251128770918764
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Arlington

In Arlington in September humidity is 78%. With an average temperature of 20°C (68°F), this humidity feels like a warm, enveloping blanket that makes exploring the sights a bit sticky, so travelers should stay hydrated and take frequent breaks in the shade.

September Average Humidity in Arlington

This chart illustrates the average monthly humidity levels in Arlington, 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 Arlington is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%87%88%81%82%81%78%78%82%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Arlington

In Arlington 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 Arlington.

Maximum UV Index Levels in Arlington for September

The chart shows the monthly maximum UV Index (UVI) for Arlington 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 Arlington typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098642
Data source: Arlington 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 Arlington Compares to Other Months

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

This table compares monthly weather conditions in Arlington, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)72 mm (2.8 inches)88%moderate
February Weather0°C (32°F)85 mm (3.3 inches)87%moderate
March Weather5°C (41°F)95 mm (3.7 inches)87%high
April Weather10°C (50°F)103 mm (4.1 inches)87%very high
May Weather17°C (63°F)136 mm (5.3 inches)81%very high
June Weather22°C (72°F)125 mm (4.9 inches)82%very high
July Weather24°C (76°F)112 mm (4.4 inches)81%very high
August Weather23°C (73°F)87 mm (3.4 inches)78%very high
September Weather20°C (68°F)70 mm (2.7 inches)78%very high
October Weather14°C (57°F)91 mm (3.6 inches)82%high
November Weather5°C (42°F)87 mm (3.4 inches)89%moderate
December Weather2°C (35°F)64 mm (2.5 inches)86%low

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