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September Weather in Sullivan, United States

Last updated: June 24, 2025

In Sullivan, United States, the average temperature in September is a pleasant 22°C (71°F). However, be prepared for fluctuations, as temperatures can dip to a minimum of 6°C (43°F) and soar to a maximum of 33°C (93°F). During this month, you can expect about 69 mm (2.7 in) of precipitation over approximately 6 days, contributing to an average humidity level of 79%.

September Temperature in Sullivan

In September in Sullivan, the average temperature is 22°C (71°F), with maximums reaching 33°C (93°F) and minimums dropping as low as 6°C (43°F). This weather makes Sullivan a great destination for travelers looking to enjoy mild and versatile conditions.

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

The chart illustrates September temperature patterns in Sullivan, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Sullivan, September typically has an average temperature of 22°C (71°F), with highs reaching up to 33°C (93°F) and lows dropping to around 6°C (43°F).
JanFebMarAprMayJunJulAugSepOctNovDec303344536675787471584237
Data source: Temperature data for Sullivan 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 Sullivan

In Sullivan in September, the precipitation amount is 69 mm (2.7 in) over a period of 6 days.

September Precipitation Trends in Sullivan

The chart displays monthly precipitation patterns in Sullivan, 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 Sullivan, September typically receives around 69 mm (2.7 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec7979127125138108116128691238964
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Sullivan

In Sullivan in September humidity is 79%. With an average temperature of 22°C (71°F), this humidity feels like a warm, sticky embrace that can make any outdoor adventure quite challenging for traveling; it's advisable to stay hydrated and take breaks in the shade to fully enjoy the sights.

September Average Humidity in Sullivan

This chart illustrates the average monthly humidity levels in Sullivan, 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 Sullivan is approximately 79%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%82%84%83%80%83%82%83%79%79%88%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Sullivan

In Sullivan 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 Sullivan.

Maximum UV Index Levels in Sullivan for September

The chart shows the monthly maximum UV Index (UVI) for Sullivan 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 Sullivan typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910111098643
Data source: Sullivan 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 Sullivan Compares to Other Months

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

This table compares monthly weather conditions in Sullivan, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-1°C (30°F)79 mm (3.1 inches)84%moderate
February Weather0°C (33°F)79 mm (3.1 inches)82%moderate
March Weather7°C (44°F)127 mm (5.0 inches)84%high
April Weather12°C (53°F)125 mm (4.9 inches)83%very high
May Weather19°C (66°F)138 mm (5.4 inches)80%very high
June Weather24°C (76°F)108 mm (4.2 inches)83%extreme
July Weather25°C (78°F)116 mm (4.6 inches)82%very high
August Weather24°C (75°F)128 mm (5.0 inches)82%very high
September Weather22°C (71°F)69 mm (2.7 inches)79%very high
October Weather14°C (58°F)123 mm (4.8 inches)79%high
November Weather6°C (42°F)89 mm (3.5 inches)88%moderate
December Weather3°C (37°F)64 mm (2.5 inches)87%moderate

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