September Weather in Alta, United States

Last updated: June 24, 2025

In Alta, United States, the average temperature in September hovers around 18°C (65°F). However, be prepared for a wide range, with minimums dipping to 1°C (35°F) and maximums soaring up to 37°C (100°F). Expect some light showers, with precipitation totaling approximately 25 mm (1.0 in) over about 3 days. The average humidity sits at a comfortable 44%, making it a pleasant time to explore!

September Temperature in Alta

In September, in Alta, the average temperature is 18°C (65°F). Maximums can reach 37°C (100°F), and minimums can be as low as 1°C (35°F). This variability makes it essential for travelers to pack layers to stay comfortable in changing conditions.

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

The chart illustrates September temperature patterns in Alta, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Alta, September typically has an average temperature of 18°C (65°F), with highs reaching up to 37°C (100°F) and lows dropping to around 1°C (35°F).

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

September Precipitation in Alta

In Alta in September, the precipitation amount is 25 mm (1.0 in) over the course of 3 days.

September Precipitation Trends in Alta

The chart displays monthly precipitation patterns in Alta, 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 Alta, September typically receives around 25 mm (1.0 inches) of precipitation spread over approximately 3 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 Alta

In Alta in September humidity is 44%. With an average temperature of 18°C (65°F), this humidity feels like a pleasant and refreshing experience for traveling, making it comfortable to explore the sights without feeling sticky or overly warm.

September Average Humidity in Alta

This chart illustrates the average monthly humidity levels in Alta, 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 Alta is approximately 44%, 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 Alta

In Alta 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 Alta.

Maximum UV Index Levels in Alta for September

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

Data source: Alta 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 Alta Compares to Other Months

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

This table compares monthly weather conditions in Alta, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	4°C (39°F)	289 mm (11.4 inches)	84%	moderate
February Weather	4°C (40°F)	295 mm (11.6 inches)	84%	moderate
March Weather	5°C (42°F)	284 mm (11.2 inches)	83%	very high
April Weather	9°C (49°F)	140 mm (5.5 inches)	81%	very high
May Weather	13°C (56°F)	90 mm (3.5 inches)	74%	extreme
June Weather	19°C (66°F)	20 mm (0.8 inches)	64%	extreme
July Weather	23°C (74°F)	3 mm (0.1 inches)	44%	extreme
August Weather	22°C (72°F)	6 mm (0.2 inches)	36%	very high
September Weather	18°C (65°F)	25 mm (1.0 inches)	44%	very high
October Weather	12°C (55°F)	77 mm (3.0 inches)	65%	high
November Weather	8°C (46°F)	163 mm (6.4 inches)	84%	moderate
December Weather	4°C (39°F)	225 mm (8.8 inches)	83%	moderate