New Castle is a city of approximately 5,400 people in Delaware, United States. Located in the Eastern Time Zone at 39.7°N latitude.
In 2025, New Castle recorded an average annual temperature of 55°F — right at the 30-year normal of 56°F. The hottest day reached 97°F in June; the coldest was 8°F in January. Total precipitation was 42 inches (drier than usual). Snowfall totaled 5 inches, below the 20-inch average. The wettest month was May.
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