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September Weather in Sussex, United States

Last updated: June 24, 2025

In September, the average temperature in Sussex, United States is a pleasant 23°C (74°F). Visitors can expect a range from a cool 9°C (48°F) to a warm 35°C (96°F). With an average humidity of 78%, the atmospheric conditions can feel quite tropical. Be prepared for some rain, as 113 mm (4.4 in) of precipitation typically falls over 9 days this month.

September Temperature in Sussex

In September in Sussex, the average temperature is 23°C (74°F). Maximums can reach 35°C (96°F), while minimums can drop as low as 9°C (48°F). Overall, this month offers a warm climate, making it an ideal time for outdoor activities and exploration.

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

The chart illustrates September temperature patterns in Sussex, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Sussex, September typically has an average temperature of 23°C (74°F), with highs reaching up to 35°C (96°F) and lows dropping to around 9°C (48°F).
JanFebMarAprMayJunJulAugSepOctNovDec414651616976807874645145
Data source: Temperature data for Sussex 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 Sussex

In Sussex in September, the precipitation amount is 113 mm (4.4 in) over a period of 9 days.

September Precipitation Trends in Sussex

The chart displays monthly precipitation patterns in Sussex, 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 Sussex, September typically receives around 113 mm (4.4 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec84105861091151161241611131047889
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Sussex

In Sussex in September humidity is 78%. With an average temperature of 23°C (74°F), this humidity feels like a warm, enveloping embrace, making travel somewhat stifling and prompting frequent breaks to hydrate and seek shade.

September Average Humidity in Sussex

This chart illustrates the average monthly humidity levels in Sussex, 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 Sussex is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%83%82%81%80%82%81%81%78%80%84%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Sussex

In Sussex 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 Sussex.

Maximum UV Index Levels in Sussex for September

The chart shows the monthly maximum UV Index (UVI) for Sussex 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 Sussex typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3679101011109853
Data source: Sussex 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 Sussex Compares to Other Months

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

This table compares monthly weather conditions in Sussex, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather5°C (42°F)84 mm (3.3 inches)84%moderate
February Weather8°C (47°F)105 mm (4.2 inches)83%high
March Weather10°C (51°F)85 mm (3.4 inches)82%high
April Weather16°C (61°F)109 mm (4.3 inches)81%very high
May Weather21°C (69°F)115 mm (4.5 inches)80%very high
June Weather24°C (76°F)116 mm (4.6 inches)82%very high
July Weather27°C (81°F)124 mm (4.9 inches)81%extreme
August Weather26°C (79°F)161 mm (6.3 inches)81%very high
September Weather23°C (74°F)113 mm (4.4 inches)78%very high
October Weather18°C (65°F)104 mm (4.1 inches)80%very high
November Weather10°C (51°F)78 mm (3.1 inches)84%moderate
December Weather7°C (45°F)89 mm (3.5 inches)84%moderate

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