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September Weather in Ukiah, United States

Last updated: June 24, 2025

In Ukiah, United States, the average temperature in September hovers around 19°C (67°F). Expect a minimum drop to 4°C (39°F) and a scorching maximum of 41°C (106°F). Precipitation is light, with an average of only 7 mm (0.3 in) over 2 days, and the air is fairly humid, boasting an average humidity of 68%.

September Temperature in Ukiah

In September in Ukiah, the average temperature is 19°C (67°F). Maximum temperatures can reach 41°C (106°F), while minimum readings can dip as low as 4°C (39°F). Be prepared for a wide range of temperatures during your travels, ensuring you pack accordingly for both warm and cooler weather.

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

The chart illustrates September temperature patterns in Ukiah, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Ukiah, September typically has an average temperature of 19°C (67°F), with highs reaching up to 41°C (106°F) and lows dropping to around 4°C (39°F).
JanFebMarAprMayJunJulAugSepOctNovDec454648535867727267595044
Data source: Temperature data for Ukiah 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 Ukiah

In Ukiah in September, the precipitation amount is 7 mm (0.3 in) over a period of 2 days.

September Precipitation Trends in Ukiah

The chart displays monthly precipitation patterns in Ukiah, 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 Ukiah, September typically receives around 7 mm (0.3 inches) of precipitation spread over approximately 2 days.
JanFebMarAprMayJunJulAugSepOctNovDec172170136795431185492115
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Ukiah

In Ukiah in September, humidity is 68%. With an average temperature of 19°C (67°F), this humidity feels like a warm, enveloping blanket, making travel pleasant yet slightly muggy, which can be refreshing while exploring but may require occasional breaks to stay comfortable.

September Average Humidity in Ukiah

This chart illustrates the average monthly humidity levels in Ukiah, 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 Ukiah is approximately 68%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%84%83%80%80%76%70%66%68%72%84%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Ukiah

In Ukiah 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 Ukiah.

Maximum UV Index Levels in Ukiah for September

The chart shows the monthly maximum UV Index (UVI) for Ukiah 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 Ukiah typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3578111111109743
Data source: Ukiah 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 Ukiah Compares to Other Months

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

This table compares monthly weather conditions in Ukiah, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather7°C (45°F)172 mm (6.8 inches)86%moderate
February Weather8°C (46°F)170 mm (6.7 inches)84%moderate
March Weather9°C (48°F)135 mm (5.3 inches)83%high
April Weather12°C (53°F)79 mm (3.1 inches)80%very high
May Weather15°C (58°F)54 mm (2.1 inches)80%extreme
June Weather19°C (67°F)3 mm (0.1 inches)76%extreme
July Weather22°C (72°F)1 mm (0.0 inches)70%extreme
August Weather22°C (72°F)1 mm (0.1 inches)66%very high
September Weather19°C (67°F)7 mm (0.3 inches)68%very high
October Weather15°C (59°F)54 mm (2.1 inches)72%high
November Weather10°C (50°F)92 mm (3.6 inches)84%moderate
December Weather7°C (45°F)115 mm (4.5 inches)84%moderate

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