Last updated: June 24, 2025
In St Johnsbury, United States, the average temperature in September hovers around 15°C (60°F). However, temperatures can vary significantly, with a minimum of -5°C (23°F) and a maximum reaching 30°C (86°F). Expect some rain, as 64 mm (2.5 in) of precipitation typically falls over 8 days, while the air maintains an average humidity of 77%.
In September in St Johnsbury, the average temperature is 15°C (60°F). Maximums can reach 30°C (86°F), while minimums can drop to as low as -5°C (23°F). Be prepared for a wide range of temperatures during your travels to St Johnsbury this September.
In St Johnsbury in September, the precipitation amount is 64 mm (2.5 in) over the course of 8 days.
In St Johnsbury in September, humidity is 77%. With an average temperature of 15°C (60°F), this humidity feels like you're wading through a warm, heavy blanket, making travel feel more exhausting and sticky than usual.
In St Johnsbury in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in St Johnsbury.
UV Risk Categories
Weather in St Johnsbury varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in St Johnsbury, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -8°C (18°F) | 80 mm (3.1 inches) | 91% | low |
| February Weather | -6°C (21°F) | 78 mm (3.1 inches) | 89% | moderate |
| March Weather | -2°C (29°F) | 69 mm (2.7 inches) | 85% | moderate |
| April Weather | 5°C (42°F) | 110 mm (4.3 inches) | 84% | very high |
| May Weather | 12°C (55°F) | 95 mm (3.7 inches) | 78% | very high |
| June Weather | 17°C (63°F) | 98 mm (3.9 inches) | 72% | very high |
| July Weather | 20°C (69°F) | 106 mm (4.2 inches) | 75% | very high |
| August Weather | 19°C (67°F) | 88 mm (3.5 inches) | 74% | very high |
| September Weather | 15°C (60°F) | 64 mm (2.5 inches) | 77% | high |
| October Weather | 9°C (48°F) | 138 mm (5.5 inches) | 85% | moderate |
| November Weather | 0°C (33°F) | 103 mm (4.0 inches) | 86% | moderate |
| December Weather | -5°C (23°F) | 85 mm (3.3 inches) | 85% | low |