December in New Haven averages a daily high of 6.8°C with nights around -1.2°C. Expect roughly 11.2 wet days totalling 97.9mm. A hard month to visit for comfort alone.
Across the year, the best time to visit New Haven is May–June.
Based on NEW HAVEN TWEED AIRPORT, CT US (6.4km), 1995–2024. 24 years of December data.