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September Weather in Walnut, United States

Last updated: June 24, 2025

In September, the average temperature in Walnut, United States is a pleasant 24°C (76°F). Expect comfortable days with temperatures ranging from a minimum of 10°C (50°F) to a maximum of 37°C (98°F). However, be prepared for some rain, as the region experiences about 122 mm (4.8 in) of precipitation spread over 8 days. With an average humidity of 70%, it's the perfect time to enjoy the unique climate of this vibrant locale!

September Temperature in Walnut

In September in Walnut, the average temperature is 24°C (76°F). Maximum temperatures can reach as high as 37°C (98°F), while minimums can drop to as low as 10°C (50°F). Be prepared for a range of weather conditions and pack accordingly for your travels!

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

The chart illustrates September temperature patterns in Walnut, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Walnut, September typically has an average temperature of 24°C (76°F), with highs reaching up to 37°C (98°F) and lows dropping to around 10°C (50°F).
JanFebMarAprMayJunJulAugSepOctNovDec424655607178817975645047
Data source: Temperature data for Walnut 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 Walnut

In Walnut in September, the precipitation amount is 122 mm (4.8 in) spread over 8 days.

September Precipitation Trends in Walnut

The chart displays monthly precipitation patterns in Walnut, 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 Walnut, September typically receives around 122 mm (4.8 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec10717615714810911213111612211379147
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Walnut

In Walnut in September, humidity is 70%. With an average temperature of 24°C (76°F), this humidity feels like a warm, enveloping blanket that can make outdoor activities feel a bit sticky and heavier, so travelers should stay hydrated and take regular breaks to enjoy the sights comfortably.

September Average Humidity in Walnut

This chart illustrates the average monthly humidity levels in Walnut, 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 Walnut is approximately 70%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%85%84%81%83%83%80%74%70%73%85%88%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Walnut

In Walnut 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 Walnut.

Maximum UV Index Levels in Walnut for September

The chart shows the monthly maximum UV Index (UVI) for Walnut 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 Walnut typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec46810111111109753
Data source: Walnut 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 Walnut Compares to Other Months

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

This table compares monthly weather conditions in Walnut, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather6°C (43°F)107 mm (4.2 inches)86%moderate
February Weather8°C (47°F)176 mm (6.9 inches)85%high
March Weather13°C (55°F)157 mm (6.2 inches)84%very high
April Weather16°C (61°F)148 mm (5.8 inches)81%very high
May Weather22°C (71°F)109 mm (4.3 inches)83%extreme
June Weather26°C (78°F)112 mm (4.4 inches)83%extreme
July Weather27°C (81°F)131 mm (5.2 inches)80%extreme
August Weather26°C (79°F)116 mm (4.6 inches)73%very high
September Weather24°C (76°F)122 mm (4.8 inches)70%very high
October Weather18°C (65°F)113 mm (4.4 inches)73%high
November Weather10°C (50°F)79 mm (3.1 inches)85%moderate
December Weather8°C (47°F)147 mm (5.8 inches)88%moderate

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