September Weather in La Mesa, United States

Last updated: June 24, 2025

In September, the average temperature in La Mesa, United States hovers around 25°C (77°F), making it a pleasant time to visit. Temperatures can fluctuate, with a minimum of 10°C (50°F) and a peak of 37°C (99°F). Expect about 30 mm (1.2 in) of precipitation over 5 days during the month, and enjoy average humidity levels at 74%, which adds to the region's unique climate experience.

September Temperature in La Mesa

In September in La Mesa, the average temperature is 25°C (77°F). Maximums can reach 37°C (99°F), while minimums can dip as low as 10°C (50°F). This makes it a perfect time for travelers to enjoy a variety of activities, from exploring the outdoors in the warm sun to experiencing cooler evenings.

September Weather in La Mesa: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in La Mesa, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In La Mesa, September typically has an average temperature of 25°C (77°F), with highs reaching up to 37°C (99°F) and lows dropping to around 10°C (50°F).

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

September Precipitation in La Mesa

In La Mesa in September, the precipitation amount is 30 mm (1.2 in) over the course of 5 days.

September Precipitation Trends in La Mesa

The chart displays monthly precipitation patterns in La Mesa, 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 La Mesa, September typically receives around 30 mm (1.2 inches) of precipitation spread over approximately 5 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 La Mesa

In La Mesa in September humidity is 74%. With an average temperature of 25°C (77°F), this humidity feels like a warm, muggy blanket wrapping around you, making travel a bit more challenging as you find yourself sticky and in need of frequent breaks to hydrate and cool down.

September Average Humidity in La Mesa

This chart illustrates the average monthly humidity levels in La Mesa, 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 La Mesa is approximately 74%, 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 La Mesa

In La Mesa 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 La Mesa.

Maximum UV Index Levels in La Mesa for September

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

Data source: La Mesa 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 La Mesa Compares to Other Months

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

This table compares monthly weather conditions in La Mesa, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	7°C (45°F)	12 mm (0.5 inches)	81%	moderate
February Weather	10°C (51°F)	13 mm (0.5 inches)	77%	high
March Weather	15°C (59°F)	17 mm (0.7 inches)	65%	very high
April Weather	20°C (68°F)	4 mm (0.1 inches)	53%	extreme
May Weather	24°C (76°F)	4 mm (0.1 inches)	51%	extreme
June Weather	29°C (84°F)	26 mm (1.0 inches)	51%	extreme
July Weather	29°C (84°F)	34 mm (1.4 inches)	60%	extreme
August Weather	28°C (83°F)	34 mm (1.4 inches)	63%	extreme
September Weather	25°C (77°F)	30 mm (1.2 inches)	74%	extreme
October Weather	19°C (67°F)	22 mm (0.9 inches)	75%	very high
November Weather	13°C (56°F)	14 mm (0.6 inches)	82%	high
December Weather	8°C (47°F)	15 mm (0.6 inches)	87%	moderate