September Weather in Bay City, United States

Last updated: June 24, 2025

In September, the average temperature in Bay City, United States is a warm 27°C (81°F), with temperatures ranging from a cool 13°C (56°F) to a scorching 36°C (97°F). Visitors can expect 165 mm (6.5 in) of precipitation spread over approximately 16 days, accompanied by an average humidity of 73%. Whether you're basking in the sun or finding shelter from the rain, Bay City offers a climate rich in diversity!

September Temperature in Bay City

In September in Bay City, the average temperature is 27°C (81°F), with maximums reaching up to 36°C (97°F) and minimums dropping as low as 13°C (56°F). It’s a great time to visit for those who enjoy warm weather with the possibility of cooler evenings.

September Weather in Bay City: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Bay City, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Bay City, September typically has an average temperature of 27°C (81°F), with highs reaching up to 36°C (97°F) and lows dropping to around 13°C (56°F).

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

September Precipitation in Bay City

In Bay City in September, the precipitation amount is 165 mm (6.5 in) over a period of 16 days.

September Precipitation Trends in Bay City

The chart displays monthly precipitation patterns in Bay City, 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 Bay City, September typically receives around 165 mm (6.5 inches) of precipitation spread over approximately 16 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 Bay City

In Bay City in September, humidity is 73%. With an average temperature of 27°C (81°F), this humidity feels like a warm blanket enveloping you, making outdoor activities feel sticky and heavy, while also requiring frequent hydration breaks to stay comfortable during your travels.

September Average Humidity in Bay City

This chart illustrates the average monthly humidity levels in Bay City, 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 Bay City is approximately 73%, 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 Bay City

In Bay City in September, the maximum UV index reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, you can check the Hourly UV Index in Bay City.

Maximum UV Index Levels in Bay City for September

The chart shows the monthly maximum UV Index (UVI) for Bay City 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 Bay City typically reaches 11, which falls under the extreme exposure category.

Data source: Bay City 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 Bay City Compares to Other Months

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

This table compares monthly weather conditions in Bay City, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	13°C (56°F)	73 mm (2.9 inches)	78%	moderate
February Weather	15°C (60°F)	72 mm (2.8 inches)	81%	very high
March Weather	19°C (67°F)	70 mm (2.7 inches)	76%	very high
April Weather	22°C (72°F)	71 mm (2.8 inches)	79%	extreme
May Weather	26°C (79°F)	137 mm (5.4 inches)	79%	extreme
June Weather	28°C (83°F)	157 mm (6.2 inches)	74%	extreme
July Weather	29°C (84°F)	145 mm (5.7 inches)	71%	extreme
August Weather	29°C (85°F)	171 mm (6.7 inches)	68%	extreme
September Weather	27°C (81°F)	165 mm (6.5 inches)	73%	extreme
October Weather	23°C (74°F)	74 mm (2.9 inches)	75%	very high
November Weather	18°C (64°F)	78 mm (3.1 inches)	78%	high
December Weather	15°C (60°F)	90 mm (3.5 inches)	84%	moderate