The highest day temperature in September 2025 was 95°F. The lowest night temperature was 57°F. The average values for day and night temperatures during September were 82.1°F и 65.1°F respectivly.

The average sea surface temperature in September 2025 for New Castle was 76.2°F. The maximum and minimum values were 74.0°F and 78.6°F respectively.

Most of the days in September are sunny but you can also expect cloudy and gloomy days.

Precipitation total in September for New Castle is 1.0 in.

The average wind speed in September is 6.5 mph. It makes September one of the most windless months of the year for New Castle.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for New Castle in September is 7.8 hours.