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September Weather in Larkspur, United States

Last updated: June 24, 2025

In September, the average temperature in Larkspur, United States hovers around 18°C (65°F), with a minimum dipping to 9°C (49°F) and a peak of 36°C (98°F). You'll experience minimal precipitation, with only about 2 mm (0.1 in) falling over the course of 0 days. Notably, the air remains quite humid, averaging 86% humidity throughout the month.

September Temperature in Larkspur

In September in Larkspur, the average temperature is 18°C (65°F). The maximum can reach 36°C (98°F) and the minimum can be as low as 9°C (49°F). This makes it an ideal time for travelers looking to experience mild weather while enjoying various outdoor activities.

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

The chart illustrates September temperature patterns in Larkspur, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Larkspur, September typically has an average temperature of 18°C (65°F), with highs reaching up to 36°C (98°F) and lows dropping to around 9°C (49°F).
JanFebMarAprMayJunJulAugSepOctNovDec515253575963636465625551
Data source: Temperature data for Larkspur 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 Larkspur

In Larkspur in September, the precipitation amount is 2 mm (0.1 in) during a span of 0 days.

September Precipitation Trends in Larkspur

The chart displays monthly precipitation patterns in Larkspur, 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 Larkspur, September typically receives around 2 mm (0.1 inches) of precipitation spread over approximately 0 days.
JanFebMarAprMayJunJulAugSepOctNovDec1111168035202212304898
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Larkspur

In Larkspur in September humidity is 86%. With an average temperature of 18°C (65°F), this humidity feels like you’re wrapped in a warm, heavy blanket, making outdoor activities feel quite muggy and sticky for traveling.

September Average Humidity in Larkspur

This chart illustrates the average monthly humidity levels in Larkspur, 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 Larkspur is approximately 86%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%82%82%79%83%84%87%87%86%80%79%79%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Larkspur

In Larkspur 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 Larkspur.

Maximum UV Index Levels in Larkspur for September

The chart shows the monthly maximum UV Index (UVI) for Larkspur 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 Larkspur typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3589101111109643
Data source: Larkspur 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 Larkspur Compares to Other Months

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

This table compares monthly weather conditions in Larkspur, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather10°C (51°F)111 mm (4.4 inches)85%moderate
February Weather11°C (52°F)116 mm (4.6 inches)82%moderate
March Weather12°C (54°F)80 mm (3.1 inches)82%very high
April Weather14°C (57°F)35 mm (1.4 inches)79%very high
May Weather15°C (60°F)20 mm (0.8 inches)83%very high
June Weather17°C (63°F)2 mm (0.1 inches)84%extreme
July Weather17°C (63°F)2 mm (0.1 inches)87%extreme
August Weather18°C (64°F)1 mm (0.1 inches)87%very high
September Weather18°C (65°F)2 mm (0.1 inches)86%very high
October Weather16°C (62°F)30 mm (1.2 inches)80%high
November Weather13°C (55°F)48 mm (1.9 inches)79%moderate
December Weather10°C (51°F)98 mm (3.9 inches)79%moderate

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