September Weather in Hayward, United States

Last updated: June 24, 2025

In Hayward, United States, the average temperature in September hovers around 20°C (68°F), with a minimum of 6°C (44°F) and a maximum reaching up to 42°C (107°F). Expect minimal precipitation of just 2 mm (0.1 in) across 0 days, making for a typically dry month. The air remains comfortably cool with an average humidity of 55%.

September Temperature in Hayward

In September in Hayward, the average temperature is 20°C (68°F). Maximums can reach 42°C (107°F), while minimums can drop as low as 6°C (44°F). It's advisable to pack layers and stay hydrated while exploring the varied climate.

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

The chart illustrates September temperature patterns in Hayward, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Hayward, September typically has an average temperature of 20°C (68°F), with highs reaching up to 42°C (107°F) and lows dropping to around 6°C (44°F).

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

September Precipitation in Hayward

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

September Precipitation Trends in Hayward

The chart displays monthly precipitation patterns in Hayward, 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 Hayward, 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 Hayward

In Hayward in September humidity is 55%. With an average temperature of 20°C (68°F), this humidity feels like a warm embrace, making it comfortable for traveling but slightly sticky, encouraging leisurely strolls and relaxed outdoor activities.

September Average Humidity in Hayward

This chart illustrates the average monthly humidity levels in Hayward, 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 Hayward 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 Hayward

In Hayward 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 Hayward.

Maximum UV Index Levels in Hayward for September

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

Data source: Hayward 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 Hayward Compares to Other Months

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

This table compares monthly weather conditions in Hayward, 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)	94 mm (3.7 inches)	82%	moderate
February Weather	11°C (52°F)	89 mm (3.5 inches)	84%	moderate
March Weather	12°C (54°F)	77 mm (3.0 inches)	82%	very high
April Weather	14°C (58°F)	30 mm (1.2 inches)	78%	very high
May Weather	16°C (61°F)	17 mm (0.7 inches)	71%	very high
June Weather	19°C (66°F)	2 mm (0.1 inches)	64%	extreme
July Weather	20°C (68°F)	0 mm (0.0 inches)	58%	extreme
August Weather	20°C (69°F)	0 mm (0.0 inches)	54%	very high
September Weather	20°C (68°F)	2 mm (0.1 inches)	55%	very high
October Weather	17°C (63°F)	22 mm (0.9 inches)	62%	high
November Weather	13°C (55°F)	38 mm (1.5 inches)	78%	moderate
December Weather	10°C (50°F)	76 mm (3.0 inches)	80%	moderate