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September Weather in Jefferson, United States

Last updated: June 24, 2025

In Jefferson, United States, the average temperature in September hovers around 20°C (68°F). During this time, you can expect temperatures to range from a chilly 4°C (40°F) to a sweltering 36°C (97°F). With an average precipitation of 100 mm (3.9 in) over 9 days, the weather can be quite dynamic. Additionally, the air tends to be fairly humid, with an average humidity level of 73%.

September Temperature in Jefferson

In September in Jefferson, the average temperature is 20°C (68°F), with maximums reaching 36°C (97°F) and minimums dropping as low as 4°C (40°F). This variety in temperatures makes Jefferson an ideal destination for travelers seeking both warm days and cooler evenings.

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

The chart illustrates September temperature patterns in Jefferson, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Jefferson, September typically has an average temperature of 20°C (68°F), with highs reaching up to 36°C (97°F) and lows dropping to around 4°C (40°F).
JanFebMarAprMayJunJulAugSepOctNovDec222339486274767368523830
Data source: Temperature data for Jefferson 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 Jefferson

In Jefferson in September, the precipitation amount is 100 mm (3.9 in) spread over 9 days.

September Precipitation Trends in Jefferson

The chart displays monthly precipitation patterns in Jefferson, 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 Jefferson, September typically receives around 100 mm (3.9 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec3139766416410476941001203637
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Jefferson

In Jefferson in September, humidity is 73%. With an average temperature of 20°C (68°F), this humidity feels like a warm embrace, making outdoor activities somewhat sticky, yet the atmosphere remains pleasant for leisurely strolls and sightseeing.

September Average Humidity in Jefferson

This chart illustrates the average monthly humidity levels in Jefferson, 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 Jefferson is approximately 73%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec78%80%77%78%77%81%81%77%73%75%85%83%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Jefferson

In Jefferson 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 Jefferson.

Maximum UV Index Levels in Jefferson for September

The chart shows the monthly maximum UV Index (UVI) for Jefferson 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 Jefferson typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec35589111098643
Data source: Jefferson 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 Jefferson Compares to Other Months

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

This table compares monthly weather conditions in Jefferson, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-6°C (22°F)31 mm (1.2 inches)78%moderate
February Weather-5°C (23°F)39 mm (1.5 inches)80%moderate
March Weather4°C (39°F)76 mm (3.0 inches)77%moderate
April Weather9°C (49°F)64 mm (2.5 inches)77%very high
May Weather16°C (62°F)163 mm (6.4 inches)77%very high
June Weather23°C (74°F)104 mm (4.1 inches)81%extreme
July Weather25°C (77°F)76 mm (3.0 inches)81%very high
August Weather23°C (73°F)94 mm (3.7 inches)77%very high
September Weather20°C (68°F)100 mm (3.9 inches)73%very high
October Weather11°C (52°F)120 mm (4.7 inches)75%high
November Weather3°C (38°F)36 mm (1.4 inches)85%moderate
December Weather-1°C (30°F)37 mm (1.5 inches)83%moderate

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