September Weather in Annandale, United States

Last updated: June 24, 2025

In Annandale, United States, the average temperature in September is a mild 17°C (63°F). Temperatures can vary significantly, with a minimum of 1°C (35°F) and a maximum reaching up to 32°C (90°F). During this time, expect about 113 mm (4.5 in) of precipitation over 10 days, alongside an average humidity level of 81%. Stay prepared for a mix of weather conditions!

September Temperature in Annandale

In September in Annandale, the average temperature is 17°C (63°F). Maximums can reach 32°C (90°F), while minimums can drop to as low as 1°C (35°F). Be prepared for a wide range of temperatures during your travels, making it essential to pack appropriately for both warm and cool conditions.

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

The chart illustrates September temperature patterns in Annandale, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Annandale, September typically has an average temperature of 17°C (63°F), with highs reaching up to 32°C (90°F) and lows dropping to around 1°C (35°F).

Data source: Temperature data for Annandale generated using information from the Copernicus Climate Change Service.

September Precipitation in Annandale

In Annandale in September, the total precipitation amount is 113 mm (4.5 in) over the course of 10 days.

September Precipitation Trends in Annandale

The chart displays monthly precipitation patterns in Annandale, 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 Annandale, September typically receives around 113 mm (4.5 inches) of precipitation spread over approximately 10 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

September Humidity in Annandale

In Annandale in September humidity is 81%. With an average temperature of 17°C (63°F), this humidity feels like a warm blanket enveloping you, making travel slightly oppressive and calling for frequent breaks in air-conditioned spaces to recharge and enjoy your journey comfortably.

September Average Humidity in Annandale

This chart illustrates the average monthly humidity levels in Annandale, 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 Annandale is approximately 81%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Annandale

In Annandale 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 Annandale.

Maximum UV Index Levels in Annandale for September

The chart shows the monthly maximum UV Index (UVI) for Annandale 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 Annandale typically reaches 7, which falls under the high exposure category.

Data source: Annandale 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 Annandale Compares to Other Months

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

This table compares monthly weather conditions in Annandale, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-9°C (15°F)	21 mm (0.8 inches)	87%	low
February Weather	-9°C (16°F)	27 mm (1.0 inches)	90%	moderate
March Weather	0°C (32°F)	53 mm (2.1 inches)	85%	moderate
April Weather	6°C (42°F)	83 mm (3.3 inches)	84%	high
May Weather	15°C (59°F)	105 mm (4.1 inches)	78%	very high
June Weather	22°C (71°F)	74 mm (2.9 inches)	80%	very high
July Weather	23°C (74°F)	93 mm (3.7 inches)	81%	very high
August Weather	21°C (70°F)	149 mm (5.9 inches)	81%	very high
September Weather	17°C (63°F)	113 mm (4.5 inches)	81%	high
October Weather	9°C (48°F)	103 mm (4.0 inches)	84%	moderate
November Weather	0°C (32°F)	31 mm (1.2 inches)	88%	moderate
December Weather	-6°C (22°F)	44 mm (1.7 inches)	84%	low