September Weather in East Palo Alto, United States

Last updated: June 24, 2025

In September, the average temperature in East Palo Alto, United States is a pleasant 18°C (66°F), making it an ideal time to explore the area. Expect temperatures to range from a cool 10°C (50°F) to a warm 39°C (103°F). With only 2 mm (0.1 in) of precipitation over 0 days, you'll likely enjoy clear skies. The average humidity sits at a comfortable 55%, ensuring a delightful atmosphere for any outdoor activities.

September Temperature in East Palo Alto

In September in East Palo Alto, the average temperature is 18°C (66°F), with maximums reaching up to 39°C (103°F) and minimums dropping as low as 10°C (50°F). Be prepared for warm days and cooler nights when planning your travel to East Palo Alto.

September Weather in East Palo Alto: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in East Palo Alto, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In East Palo Alto, September typically has an average temperature of 18°C (66°F), with highs reaching up to 39°C (103°F) and lows dropping to around 10°C (50°F).

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

September Precipitation in East Palo Alto

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

September Precipitation Trends in East Palo Alto

The chart displays monthly precipitation patterns in East Palo Alto, 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 East Palo Alto, 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.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in East Palo Alto

In East Palo Alto in September humidity is 55%. With an average temperature of 18°C (66°F), this humidity feels like a refreshing embrace, making for comfortable travels as long as you stay hydrated and enjoy the mild weather.

September Average Humidity in East Palo Alto

This chart illustrates the average monthly humidity levels in East Palo Alto, 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 East Palo Alto 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 East Palo Alto

In East Palo Alto 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 East Palo Alto.

Maximum UV Index Levels in East Palo Alto for September

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

Data source: East Palo Alto 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 East Palo Alto Compares to Other Months

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

This table compares monthly weather conditions in East Palo Alto, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	11°C (52°F)	105 mm (4.1 inches)	82%	moderate
February Weather	11°C (53°F)	100 mm (3.9 inches)	84%	moderate
March Weather	12°C (54°F)	86 mm (3.4 inches)	82%	very high
April Weather	13°C (57°F)	33 mm (1.3 inches)	78%	very high
May Weather	15°C (59°F)	24 mm (0.9 inches)	71%	very high
June Weather	17°C (63°F)	2 mm (0.1 inches)	64%	extreme
July Weather	17°C (63°F)	0 mm (0.0 inches)	58%	extreme
August Weather	18°C (65°F)	0 mm (0.0 inches)	54%	very high
September Weather	18°C (66°F)	2 mm (0.1 inches)	55%	very high
October Weather	17°C (63°F)	24 mm (0.9 inches)	62%	high
November Weather	13°C (56°F)	47 mm (1.9 inches)	78%	moderate
December Weather	11°C (52°F)	88 mm (3.5 inches)	80%	moderate