September Weather in Allen, United States

Last updated: June 24, 2025

In September, the average temperature in Allen, United States hovers around 25°C (77°F), creating a pleasantly warm atmosphere. However, be prepared for a temperature range that can dip to a chilly 9°C (48°F) or soar up to a scorching 38°C (100°F). With an average precipitation of 106 mm (4.2 in) spread over about 6 days, you might want to pack an umbrella. The air is also relatively humid, with an average humidity level of 64%, adding to that tropical feel!

September Temperature in Allen

In September in Allen, the average temperature is 25°C (77°F), with maximums reaching 38°C (100°F) and minimums dropping as low as 9°C (48°F). This makes it a great time for travelers looking to enjoy warm weather while also being prepared for cooler evenings.

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

The chart illustrates September temperature patterns in Allen, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Allen, September typically has an average temperature of 25°C (77°F), with highs reaching up to 38°C (100°F) and lows dropping to around 9°C (48°F).

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

September Precipitation in Allen

In Allen in September, the precipitation amount is 106 mm (4.2 in) over the course of 6 days.

September Precipitation Trends in Allen

The chart displays monthly precipitation patterns in Allen, 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 Allen, September typically receives around 106 mm (4.2 inches) of precipitation spread over approximately 6 days.

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

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in Allen

In Allen in September, humidity is 64%. With an average temperature of 25°C (77°F), this humidity feels like a warm embrace, making outdoor excursions feel a bit heavier, yet still inviting for travelers seeking a vibrant atmosphere.

September Average Humidity in Allen

This chart illustrates the average monthly humidity levels in Allen, 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 Allen is approximately 64%, 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 Allen

In Allen 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 Allen.

Maximum UV Index Levels in Allen for September

The chart shows the monthly maximum UV Index (UVI) for Allen 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 Allen typically reaches 9, which falls under the very high exposure category.

Data source: Allen 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 Allen Compares to Other Months

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

This table compares monthly weather conditions in Allen, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	5°C (42°F)	68 mm (2.7 inches)	79%	moderate
February Weather	6°C (44°F)	81 mm (3.2 inches)	78%	high
March Weather	13°C (56°F)	89 mm (3.5 inches)	75%	high
April Weather	16°C (61°F)	136 mm (5.4 inches)	75%	very high
May Weather	21°C (71°F)	171 mm (6.7 inches)	83%	very high
June Weather	26°C (79°F)	77 mm (3.0 inches)	81%	extreme
July Weather	28°C (83°F)	68 mm (2.7 inches)	78%	extreme
August Weather	27°C (82°F)	70 mm (2.8 inches)	68%	extreme
September Weather	25°C (77°F)	106 mm (4.2 inches)	64%	very high
October Weather	17°C (64°F)	117 mm (4.6 inches)	71%	high
November Weather	11°C (52°F)	51 mm (2.0 inches)	82%	moderate
December Weather	8°C (47°F)	57 mm (2.2 inches)	87%	moderate