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September Weather in New Castle, United States

Last updated: June 24, 2025

In New Castle, United States, the average temperature in September is a pleasant 20°C (68°F). However, temperatures can vary significantly, with a minimum of 3°C (37°F) and a maximum reaching up to 34°C (93°F). Expect around 114 mm (4.5 in) of precipitation over 9 days, and a comfortable average humidity of 68%.

September Temperature in New Castle

In September, in New Castle, the average temperature is 20°C (68°F), with maximums reaching 34°C (93°F) and minimums dropping as low as 3°C (37°F). This makes New Castle a great destination for travelers looking to enjoy mild weather with the possibility of warm afternoons and cool evenings.

September Weather in New Castle: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in New Castle, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In New Castle, September typically has an average temperature of 20°C (68°F), with highs reaching up to 34°C (93°F) and lows dropping to around 3°C (37°F).
JanFebMarAprMayJunJulAugSepOctNovDec354045546370757368584439
Data source: Temperature data for New Castle 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 New Castle

In New Castle in September, the precipitation amount is 114 mm (4.5 in) over the course of 9 days.

September Precipitation Trends in New Castle

The chart displays monthly precipitation patterns in New Castle, 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 New Castle, September typically receives around 114 mm (4.5 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec7411182120147117781091141147598
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in New Castle

In New Castle in September humidity is 68%. With an average temperature of 20°C (68°F), this humidity feels like a warm embrace, making it ideal for leisurely strolls while also prompting travelers to stay hydrated and seek out refreshing breaks from the heat.

September Average Humidity in New Castle

This chart illustrates the average monthly humidity levels in New Castle, 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 New Castle is approximately 68%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%87%86%84%83%83%79%66%68%78%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in New Castle

In New Castle 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 New Castle.

Maximum UV Index Levels in New Castle for September

The chart shows the monthly maximum UV Index (UVI) for New Castle 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 New Castle typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec36810101111109753
Data source: New Castle 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 New Castle Compares to Other Months

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

This table compares monthly weather conditions in New Castle, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather2°C (35°F)73 mm (2.9 inches)87%moderate
February Weather5°C (41°F)111 mm (4.4 inches)87%high
March Weather7°C (46°F)82 mm (3.2 inches)86%very high
April Weather12°C (55°F)120 mm (4.7 inches)84%very high
May Weather17°C (64°F)147 mm (5.8 inches)83%very high
June Weather21°C (70°F)117 mm (4.6 inches)83%extreme
July Weather24°C (75°F)78 mm (3.1 inches)79%extreme
August Weather23°C (73°F)109 mm (4.3 inches)66%very high
September Weather20°C (68°F)114 mm (4.5 inches)68%very high
October Weather15°C (58°F)114 mm (4.5 inches)78%high
November Weather6°C (44°F)75 mm (3.0 inches)89%moderate
December Weather4°C (39°F)98 mm (3.9 inches)86%moderate

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