September Weather in Yankton, United States

Last updated: June 24, 2025

In September, the average temperature in Yankton, United States is a pleasant 20°C (67°F). Temperatures can vary, with minimums dipping to 5°C (42°F) and maximums soaring as high as 34°C (94°F). Expect some rain, as 77 mm (3.0 in) of precipitation typically falls over about 8 days, accompanied by an average humidity level of 75%.

September Temperature in Yankton

In September in Yankton, the average temperature is 20°C (67°F). The maximum can reach 34°C (94°F), and the minimum can be as low as 5°C (42°F). This wide range of temperatures makes Yankton an ideal destination for travelers seeking both warm days and cooler evenings.

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

The chart illustrates September temperature patterns in Yankton, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Yankton, September typically has an average temperature of 20°C (67°F), with highs reaching up to 34°C (94°F) and lows dropping to around 5°C (42°F).

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

September Precipitation in Yankton

In Yankton in September, the precipitation amount is 77 mm (3.0 in) distributed over 8 days.

September Precipitation Trends in Yankton

The chart displays monthly precipitation patterns in Yankton, 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 Yankton, September typically receives around 77 mm (3.0 inches) of precipitation spread over approximately 8 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 Yankton

In Yankton in September humidity is 75%. With an average temperature of 20°C (67°F), this humidity feels like a warm, enveloping blanket that makes outdoor activities more strenuous, causing travelers to feel sticky and fatigued faster.

September Average Humidity in Yankton

This chart illustrates the average monthly humidity levels in Yankton, 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 Yankton is approximately 75%, 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 Yankton

In Yankton 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 Yankton.

Maximum UV Index Levels in Yankton for September

The chart shows the monthly maximum UV Index (UVI) for Yankton 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 Yankton typically reaches 8, which falls under the very high exposure category.

Data source: Yankton 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 Yankton Compares to Other Months

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

This table compares monthly weather conditions in Yankton, 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 (23°F)	24 mm (0.9 inches)	77%	moderate
February Weather	-5°C (22°F)	25 mm (1.0 inches)	81%	moderate
March Weather	3°C (38°F)	77 mm (3.0 inches)	71%	high
April Weather	8°C (46°F)	80 mm (3.1 inches)	75%	very high
May Weather	15°C (60°F)	154 mm (6.1 inches)	74%	very high
June Weather	23°C (74°F)	90 mm (3.5 inches)	82%	extreme
July Weather	25°C (77°F)	88 mm (3.5 inches)	84%	very high
August Weather	23°C (73°F)	95 mm (3.8 inches)	82%	very high
September Weather	20°C (67°F)	77 mm (3.0 inches)	75%	very high
October Weather	10°C (50°F)	76 mm (3.0 inches)	72%	moderate
November Weather	3°C (38°F)	22 mm (0.9 inches)	81%	moderate
December Weather	-2°C (28°F)	43 mm (1.7 inches)	79%	low