September Weather in Gilroy, United States

Last updated: June 24, 2025

In Gilroy, United States, the average temperature in September is a pleasant 19°C (67°F). While you can expect minimum temperatures to dip as low as 7°C (45°F), it’s possible for highs to reach an impressive 39°C (102°F). Rain is rarely a concern, with just 2 mm (0.1 in) of precipitation over 0 days and an average humidity of 55%. Enjoy the warmth!

September Temperature in Gilroy

In September in Gilroy, the average temperature is 19°C (67°F). The maximum can reach 39°C (102°F), while the minimum can drop as low as 7°C (45°F). Be sure to pack accordingly to enjoy a comfortable trip!

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

The chart illustrates September temperature patterns in Gilroy, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Gilroy, September typically has an average temperature of 19°C (67°F), with highs reaching up to 39°C (102°F) and lows dropping to around 7°C (45°F).

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

September Precipitation in Gilroy

In Gilroy in September, the precipitation amount is 2 mm (0.1 in) during a span of 0 days.

September Precipitation Trends in Gilroy

The chart displays monthly precipitation patterns in Gilroy, 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 Gilroy, September typically receives around 2 mm (0.1 inches) of precipitation spread over approximately 0 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 Gilroy

In Gilroy in September, humidity is 55%. With an average temperature of 19°C (67°F), this humidity feels like a refreshing embrace, perfect for leisurely strolls and outdoor adventures.

September Average Humidity in Gilroy

This chart illustrates the average monthly humidity levels in Gilroy, 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 Gilroy is approximately 55%, 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 Gilroy

In Gilroy 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 Gilroy.

Maximum UV Index Levels in Gilroy for September

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

Data source: Gilroy 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 Gilroy Compares to Other Months

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

This table compares monthly weather conditions in Gilroy, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	10°C (50°F)	103 mm (4.0 inches)	82%	moderate
February Weather	11°C (52°F)	79 mm (3.1 inches)	84%	moderate
March Weather	12°C (53°F)	73 mm (2.9 inches)	82%	very high
April Weather	14°C (57°F)	26 mm (1.0 inches)	78%	very high
May Weather	15°C (60°F)	15 mm (0.6 inches)	71%	extreme
June Weather	18°C (65°F)	1 mm (0.0 inches)	64%	extreme
July Weather	19°C (67°F)	1 mm (0.0 inches)	58%	extreme
August Weather	20°C (68°F)	1 mm (0.0 inches)	54%	very high
September Weather	19°C (67°F)	2 mm (0.1 inches)	55%	very high
October Weather	17°C (62°F)	17 mm (0.7 inches)	62%	high
November Weather	13°C (55°F)	30 mm (1.2 inches)	78%	moderate
December Weather	10°C (50°F)	79 mm (3.1 inches)	80%	moderate