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September Weather in Fort Smith, United States

Last updated: June 24, 2025

In September, the average temperature in Fort Smith, United States is a pleasant 24°C (76°F). However, temperatures can range from a cool 8°C (47°F) to a sweltering 37°C (99°F). Expect about 78 mm (3.1 in) of precipitation over approximately 6 days, and enjoy an average humidity of 59%.

September Temperature in Fort Smith

In September in Fort Smith, the average temperature is 24°C (76°F). Maximums can reach 37°C (99°F), while minimums can dip to as low as 8°C (47°F). Be sure to pack accordingly, as the weather can vary significantly, making it essential to dress in layers.

September Weather in Fort Smith: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Fort Smith, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Fort Smith, September typically has an average temperature of 24°C (76°F), with highs reaching up to 37°C (99°F) and lows dropping to around 8°C (47°F).
JanFebMarAprMayJunJulAugSepOctNovDec404354596978817975625045
Data source: Temperature data for Fort Smith 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 Fort Smith

In Fort Smith in September, the precipitation amount is 78 mm (3.1 in) spread over 6 days.

September Precipitation Trends in Fort Smith

The chart displays monthly precipitation patterns in Fort Smith, 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 Fort Smith, September typically receives around 78 mm (3.1 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec981231421572139198132781518798
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Fort Smith

In Fort Smith in September humidity is 59%. With an average temperature of 24°C (76°F), this humidity feels like a comfortable, refreshing embrace, making it ideal for leisurely strolls and outdoor explorations.

September Average Humidity in Fort Smith

This chart illustrates the average monthly humidity levels in Fort Smith, 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 Fort Smith is approximately 59%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%79%77%78%82%81%75%61%59%69%82%88%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Fort Smith

In Fort Smith 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 Fort Smith.

Maximum UV Index Levels in Fort Smith for September

The chart shows the monthly maximum UV Index (UVI) for Fort Smith 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 Fort Smith typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec46710111111109754
Data source: Fort Smith 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 Fort Smith Compares to Other Months

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

This table compares monthly weather conditions in Fort Smith, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather4°C (40°F)98 mm (3.9 inches)82%moderate
February Weather6°C (43°F)123 mm (4.8 inches)79%high
March Weather12°C (54°F)141 mm (5.6 inches)77%high
April Weather15°C (60°F)157 mm (6.2 inches)78%very high
May Weather21°C (70°F)213 mm (8.4 inches)82%extreme
June Weather25°C (78°F)91 mm (3.6 inches)81%extreme
July Weather27°C (81°F)98 mm (3.8 inches)75%extreme
August Weather26°C (79°F)132 mm (5.2 inches)61%very high
September Weather24°C (76°F)78 mm (3.1 inches)59%very high
October Weather17°C (63°F)151 mm (5.9 inches)69%high
November Weather10°C (50°F)87 mm (3.4 inches)82%moderate
December Weather7°C (46°F)98 mm (3.9 inches)87%moderate

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