September Weather in Iowa, United States

Last updated: June 24, 2025

In Iowa, United States, the average temperature in September hovers around 26°C (80°F), making it a comfortable time to visit. However, be prepared for temperatures that can dip to a cool 13°C (56°F) or soar up to a steamy 35°C (96°F). Expect about 163 mm (6.4 in) of rain spread across 13 days, contributing to an average humidity of 72%. Pack accordingly to enjoy all that this vibrant location has to offer!

September Temperature in Iowa

In September in Iowa, the average temperature is 26°C (80°F). The maximum can reach 35°C (96°F), and the minimum can be as low as 13°C (56°F). This makes Iowa a great destination for travelers looking to enjoy warm weather with a comfortable range of temperatures.

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

The chart illustrates September temperature patterns in Iowa, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Iowa, September typically has an average temperature of 26°C (80°F), with highs reaching up to 35°C (96°F) and lows dropping to around 13°C (56°F).

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

September Precipitation in Iowa

In Iowa in September, the total precipitation amount is 163 mm (6.4 in), occurring over the course of 13 days.

September Precipitation Trends in Iowa

The chart displays monthly precipitation patterns in Iowa, 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 Iowa, September typically receives around 163 mm (6.4 inches) of precipitation spread over approximately 13 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 Iowa

In Iowa in September, humidity is 72%. With an average temperature of 26°C (80°F), this humidity feels like a warm embrace, making traveling feel a bit heavier, yet invigorating as you navigate the vibrant atmosphere, surrounded by the rich scents and lively sounds of the locale.

September Average Humidity in Iowa

This chart illustrates the average monthly humidity levels in Iowa, 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 Iowa is approximately 72%, 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 Iowa

In Iowa in September, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Iowa.

Maximum UV Index Levels in Iowa for September

The chart shows the monthly maximum UV Index (UVI) for Iowa 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 Iowa typically reaches 10, which falls under the very high exposure category.

Data source: Iowa 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 Iowa Compares to Other Months

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

This table compares monthly weather conditions in Iowa, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	12°C (53°F)	117 mm (4.6 inches)	81%	moderate
February Weather	14°C (58°F)	107 mm (4.2 inches)	81%	very high
March Weather	18°C (65°F)	70 mm (2.7 inches)	79%	very high
April Weather	20°C (69°F)	155 mm (6.1 inches)	80%	very high
May Weather	25°C (77°F)	193 mm (7.6 inches)	81%	extreme
June Weather	27°C (81°F)	163 mm (6.4 inches)	76%	extreme
July Weather	28°C (83°F)	158 mm (6.2 inches)	73%	extreme
August Weather	28°C (83°F)	179 mm (7.1 inches)	71%	extreme
September Weather	26°C (80°F)	163 mm (6.4 inches)	72%	very high
October Weather	22°C (72°F)	122 mm (4.8 inches)	73%	very high
November Weather	16°C (60°F)	75 mm (2.9 inches)	83%	high
December Weather	14°C (57°F)	119 mm (4.7 inches)	88%	moderate