With a population of around 5,000, Mendham sits in New Jersey, United States. The city operates in the Eastern Time Zone.
In 2025, Mendham recorded an average annual temperature of 53°F — right at the 30-year normal of 53°F. The hottest day reached 99°F in June; the coldest was 3°F in January. Total precipitation was 42 inches (drier than usual). The wettest month was May.
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