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September Weather in Clear Lake, United States

Last updated: June 24, 2025

In September, the average temperature in Clear Lake, United States hovers around 17°C (63°F), with daily fluctuations ranging from a chilly 1°C (35°F) to a warm 32°C (90°F). During this period, expect about 91 mm (3.6 in) of precipitation spread over 9 days, contributing to an average humidity of 82%. Stay prepared for varying weather conditions!

September Temperature in Clear Lake

In September in Clear Lake, the average temperature is 17°C (63°F). Maximums can reach 32°C (90°F), while minimums can drop to as low as 1°C (35°F). Be prepared for a wide range of temperatures during your travels, making it essential to pack appropriately for both warm and cool conditions.

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

The chart illustrates September temperature patterns in Clear Lake, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Clear Lake, 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 (35°F).
JanFebMarAprMayJunJulAugSepOctNovDec151431405670736962453223
Data source: Temperature data for Clear 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 Clear Lake

In Clear Lake in September, the precipitation amount is 91 mm (3.6 in) spread over 9 days.

September Precipitation Trends in Clear Lake

The chart displays monthly precipitation patterns in Clear 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 Clear Lake, September typically receives around 91 mm (3.6 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec2319557298869612491802834
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Clear Lake

In Clear Lake in September, humidity is 82%. With an average temperature of 17°C (63°F), this humidity feels like a warm blanket wrapping around you—comfortable yet heavy, making outdoor activities more taxing and requiring frequent breaks for hydration.

September Average Humidity in Clear Lake

This chart illustrates the average monthly humidity levels in Clear 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 Clear Lake is approximately 82%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%89%81%82%76%81%82%83%82%82%87%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Clear Lake

In Clear Lake 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 Clear Lake.

Maximum UV Index Levels in Clear Lake for September

The chart shows the monthly maximum UV Index (UVI) for Clear 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 Clear Lake typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3568910998532
Data source: Clear 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 Clear Lake Compares to Other Months

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

This table compares monthly weather conditions in Clear Lake, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-10°C (15°F)23 mm (0.9 inches)85%moderate
February Weather-10°C (15°F)19 mm (0.7 inches)89%moderate
March Weather-1°C (31°F)55 mm (2.2 inches)81%high
April Weather5°C (41°F)72 mm (2.8 inches)82%very high
May Weather13°C (56°F)98 mm (3.9 inches)76%very high
June Weather21°C (70°F)86 mm (3.4 inches)81%very high
July Weather23°C (73°F)96 mm (3.8 inches)82%very high
August Weather21°C (69°F)124 mm (4.9 inches)83%very high
September Weather17°C (63°F)91 mm (3.6 inches)82%very high
October Weather7°C (46°F)80 mm (3.1 inches)82%moderate
November Weather0°C (33°F)28 mm (1.1 inches)87%moderate
December Weather-5°C (24°F)34 mm (1.3 inches)84%low

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