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September Weather in Upper Lake, United States

Last updated: June 24, 2025

In Upper Lake, United States, the average temperature in September reaches a comfortable 20°C (69°F). However, be prepared for extremes, as temperatures can dip to a brisk 3°C (38°F) or soar up to a sizzling 40°C (105°F). With an average humidity of 68%, you might find the air a bit muggy. Additionally, you can expect some light rain, with an average precipitation amount of 6 mm (0.2 in) over the course of 1 day.

September Temperature in Upper Lake

In September in Upper Lake, the average temperature is 20°C (69°F). Maximum temperatures can reach up to 40°C (105°F), while minimum temperatures can drop as low as 3°C (38°F). Travelers should pack for both warm days and cool nights to fully enjoy their stay.

September Weather in Upper Lake: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Upper Lake, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Upper Lake, September typically has an average temperature of 20°C (69°F), with highs reaching up to 40°C (105°F) and lows dropping to around 3°C (38°F).
JanFebMarAprMayJunJulAugSepOctNovDec444547535969767568595044
Data source: Temperature data for Upper Lake 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 Upper Lake

In Upper Lake in September, the precipitation amount is 6 mm (0.2 in) over the course of 1 day.

September Precipitation Trends in Upper Lake

The chart displays monthly precipitation patterns in Upper Lake, 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 Upper Lake, September typically receives around 6 mm (0.2 inches) of precipitation spread over approximately 1 days.
JanFebMarAprMayJunJulAugSepOctNovDec164167119654740265280110
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Upper Lake

In Upper Lake in September, humidity is 68%. With an average temperature of 20°C (69°F), this humidity feels like a warm embrace, making outdoor exploration both refreshing and slightly sticky, requiring occasional breaks in the shade to stay comfortable while traveling.

September Average Humidity in Upper Lake

This chart illustrates the average monthly humidity levels in Upper Lake, 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 Upper Lake 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 Upper Lake

In Upper Lake 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 Upper Lake.

Maximum UV Index Levels in Upper Lake for September

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

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

This table compares monthly weather conditions in Upper Lake, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather7°C (44°F)164 mm (6.5 inches)86%moderate
February Weather7°C (46°F)167 mm (6.6 inches)84%moderate
March Weather8°C (47°F)119 mm (4.7 inches)83%high
April Weather12°C (53°F)65 mm (2.6 inches)80%very high
May Weather15°C (59°F)47 mm (1.9 inches)80%extreme
June Weather20°C (69°F)4 mm (0.1 inches)76%extreme
July Weather24°C (76°F)0 mm (0.0 inches)70%extreme
August Weather24°C (75°F)2 mm (0.1 inches)66%very high
September Weather20°C (69°F)6 mm (0.2 inches)68%very high
October Weather15°C (60°F)52 mm (2.0 inches)72%high
November Weather10°C (50°F)80 mm (3.2 inches)84%moderate
December Weather7°C (44°F)110 mm (4.3 inches)84%moderate

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