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September Weather in Sullivan, United States

Last updated: June 24, 2025

In Sullivan, United States, the average temperature in September hovers around 22°C (72°F). However, be prepared for a range of weather, with minimum temperatures dipping to 7°C (45°F) and soaring to a warm 35°C (95°F). During this month, expect approximately 53 mm (2.1 in) of precipitation spread over 6 days, and enjoy an average humidity of 76%, contributing to a pleasantly warm atmosphere.

September Temperature in Sullivan

In September in Sullivan, the average temperature is 22°C (72°F). The maximum can reach 35°C (95°F), while the minimum can drop to as low as 7°C (45°F). This diverse temperature range makes it a perfect time for travelers to enjoy both warm days and cooler evenings while exploring the sights.

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 (72°F), with highs reaching up to 35°C (95°F) and lows dropping to around 7°C (45°F).
JanFebMarAprMayJunJulAugSepOctNovDec333647556675797572594540
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 53 mm (2.1 in) over a span 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 53 mm (2.1 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec768412813216587100127531076856
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 76%. With an average temperature of 22°C (72°F), this humidity feels like a warm embrace, making travel slightly uncomfortable as you navigate through the thick, saturated air.

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 76%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%80%80%80%82%83%81%80%76%76%85%86%
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 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 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 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3569101111109753
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 Weather1°C (33°F)76 mm (3.0 inches)82%moderate
February Weather2°C (36°F)84 mm (3.3 inches)80%moderate
March Weather8°C (48°F)128 mm (5.1 inches)80%high
April Weather13°C (55°F)132 mm (5.2 inches)80%very high
May Weather19°C (66°F)165 mm (6.5 inches)82%very high
June Weather24°C (76°F)87 mm (3.4 inches)83%extreme
July Weather26°C (79°F)100 mm (3.9 inches)81%extreme
August Weather24°C (76°F)126 mm (5.0 inches)80%very high
September Weather22°C (72°F)53 mm (2.1 inches)76%very high
October Weather15°C (59°F)107 mm (4.2 inches)76%high
November Weather7°C (45°F)68 mm (2.7 inches)85%moderate
December Weather4°C (40°F)56 mm (2.2 inches)86%moderate

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