Last updated: June 24, 2025
In September, the average temperature in New Haven, United States hovers around 20°C (68°F), offering a pleasant climate for visitors. Expect minimums to dip to 4°C (39°F), while maximums can soar to an impressive 33°C (93°F). During this month, precipitation totals about 65 mm (2.5 in), spread over roughly 8 days, and the average humidity levels sit at a comfortable 78%.
In September in New Haven, the average temperature is 20°C (68°F). Maximum temperatures can reach up to 33°C (93°F), while minimum temperatures can drop as low as 4°C (39°F). This range makes it an ideal time for travelers to explore the area's outdoor attractions while being prepared for both warm and cooler moments.
In New Haven in September, the precipitation amount is 65 mm (2.5 in) over a span of 8 days.
In New Haven in September humidity is 78%. With an average temperature of 20°C (68°F), this humidity feels like a warm, enveloping blanket that makes exploring the sights a bit sticky, so travelers should stay hydrated and take frequent breaks in the shade.
In New Haven in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in New Haven.
UV Risk Categories
Weather in New Haven varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in New Haven, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -2°C (29°F) | 74 mm (2.9 inches) | 85% | moderate |
| February Weather | -1°C (31°F) | 80 mm (3.2 inches) | 85% | moderate |
| March Weather | 5°C (41°F) | 102 mm (4.0 inches) | 86% | high |
| April Weather | 10°C (50°F) | 92 mm (3.6 inches) | 87% | very high |
| May Weather | 17°C (63°F) | 127 mm (5.0 inches) | 81% | very high |
| June Weather | 22°C (72°F) | 121 mm (4.8 inches) | 82% | very high |
| July Weather | 24°C (76°F) | 104 mm (4.1 inches) | 81% | very high |
| August Weather | 23°C (74°F) | 96 mm (3.8 inches) | 79% | very high |
| September Weather | 20°C (68°F) | 65 mm (2.5 inches) | 78% | very high |
| October Weather | 14°C (57°F) | 101 mm (4.0 inches) | 81% | high |
| November Weather | 5°C (41°F) | 82 mm (3.2 inches) | 89% | moderate |
| December Weather | 1°C (35°F) | 61 mm (2.4 inches) | 86% | low |