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September Weather in Hayward, United States

Last updated: June 24, 2025

In September, the average temperature in Hayward, United States hovers around 16°C (61°F). However, don't be surprised if you experience a minimum of 1°C (34°F) and occasionally bask in highs of 31°C (89°F). Expect around 104 mm (4.1 in) of rain spread over 11 days, while the air remains quite humid at an average of 80%.

September Temperature in Hayward

In September in Hayward, the average temperature is 16°C (61°F). Maximums can reach 31°C (89°F), and minimums can dip as low as 1°C (34°F). This variability makes it essential to pack layers for your travels.

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 16°C (61°F), with highs reaching up to 31°C (89°F) and lows dropping to around 1°C (34°F).
JanFebMarAprMayJunJulAugSepOctNovDec141429405667716761463021
Data source: Temperature data for Hayward generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Hayward

In Hayward in September, the precipitation amount is 104 mm (4.1 in) over the course of 11 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 104 mm (4.1 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec2640498810494100113104944661
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Hayward

In Hayward in September, humidity is 80%. With an average temperature of 16°C (61°F), this humidity feels like a warm blanket wrapped around you, making sightseeing a sweat-inducing challenge but also lending a lush vibrancy to the surroundings that can enhance your travel experience.

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 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%89%86%85%79%80%80%78%80%84%89%85%
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 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more 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 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2457910987532
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.
 TemperaturePrecipitationHumidityUV
January Weather-10°C (14°F)26 mm (1.0 inches)88%low
February Weather-10°C (15°F)40 mm (1.6 inches)89%moderate
March Weather-2°C (29°F)49 mm (1.9 inches)86%moderate
April Weather4°C (40°F)88 mm (3.5 inches)85%high
May Weather13°C (56°F)104 mm (4.1 inches)79%very high
June Weather19°C (67°F)94 mm (3.7 inches)80%very high
July Weather22°C (71°F)100 mm (3.9 inches)80%very high
August Weather20°C (68°F)113 mm (4.5 inches)78%very high
September Weather16°C (61°F)104 mm (4.1 inches)80%high
October Weather8°C (46°F)94 mm (3.7 inches)84%moderate
November Weather-1°C (31°F)46 mm (1.8 inches)89%moderate
December Weather-6°C (21°F)61 mm (2.4 inches)85%low

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