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September Weather in Campbell, United States

Last updated: June 24, 2025

In September, the average temperature in Campbell, United States is a pleasant 17°C (63°F), with a comfortable humidity level of 78%. Expect temperatures to range from a chilly minimum of 1°C (34°F) to a warm maximum of 32°C (90°F). Be prepared for some rain, as the area averages 84 mm (3.3 in) of precipitation over 9 days this month.

September Temperature in Campbell

In September in Campbell, the average temperature is 17°C (63°F). Maximums can reach 32°C (90°F), while minimums can drop as low as 1°C (34°F). Be prepared for a range of temperatures during your travels.

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

The chart illustrates September temperature patterns in Campbell, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Campbell, September typically has an average temperature of 17°C (63°F), with highs reaching up to 32°C (90°F) and lows dropping to around 1°C (34°F).
JanFebMarAprMayJunJulAugSepOctNovDec252734455766716963523730
Data source: Temperature data for Campbell 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 Campbell

In Campbell in September, the precipitation amount is 84 mm (3.3 in) spread over 9 days.

September Precipitation Trends in Campbell

The chart displays monthly precipitation patterns in Campbell, 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 Campbell, September typically receives around 84 mm (3.3 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec6782761081159513378841287582
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Campbell

In Campbell in September, humidity is 78%. With an average temperature of 17°C (63°F), this humidity feels like a warm, enveloping blanket, making traveling slightly uncomfortable as you navigate the sticky air, prompting the need for frequent breaks in cooler, shaded areas.

September Average Humidity in Campbell

This chart illustrates the average monthly humidity levels in Campbell, 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 Campbell is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec90%90%87%88%82%79%78%76%78%84%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Campbell

In Campbell in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Campbell.

Maximum UV Index Levels in Campbell for September

The chart shows the monthly maximum UV Index (UVI) for Campbell 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 Campbell typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec346810101098642
Data source: Campbell 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 Campbell Compares to Other Months

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

This table compares monthly weather conditions in Campbell, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-4°C (25°F)67 mm (2.6 inches)90%moderate
February Weather-3°C (28°F)82 mm (3.2 inches)90%moderate
March Weather1°C (35°F)75 mm (3.0 inches)87%high
April Weather7°C (46°F)108 mm (4.3 inches)88%very high
May Weather14°C (58°F)115 mm (4.5 inches)82%very high
June Weather19°C (66°F)95 mm (3.7 inches)79%very high
July Weather22°C (71°F)133 mm (5.2 inches)78%very high
August Weather21°C (69°F)78 mm (3.1 inches)76%very high
September Weather17°C (63°F)84 mm (3.3 inches)78%very high
October Weather11°C (53°F)128 mm (5.0 inches)84%high
November Weather3°C (38°F)75 mm (3.0 inches)89%moderate
December Weather-1°C (31°F)82 mm (3.2 inches)86%low

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