Last updated: June 24, 2025
In September, the average temperature in Hyannis, United States is a pleasant 18°C (65°F), making it a delightful time to explore. Temperatures can range from a chilly 1°C (33°F) to a sweltering 36°C (97°F), so be prepared for a bit of a climate rollercoaster! Expect a total precipitation of 46 mm (1.8 in) over approximately 5 rainy days, contributing to the area's lush beauty. With an average humidity of 70%, embracing the refreshing atmosphere is essential.
In September in Hyannis, the average temperature is 18°C (65°F), with maximums reaching 36°C (97°F) and minimums dropping as low as 1°C (33°F). Travelers should be prepared for both warm days and chilly nights, making layered clothing a wise choice.
In Hyannis in September, the precipitation amount is 46 mm (1.8 in) recorded over a span of 5 days.
In Hyannis in September humidity is 70%. With an average temperature of 18°C (65°F), this humidity feels like a warm embrace, making it quite comfortable for traveling, though it can leave you feeling slightly sticky if you're on the move for too long.
In Hyannis in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Hyannis.
UV Risk Categories
Weather in Hyannis varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Hyannis, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -3°C (27°F) | 14 mm (0.5 inches) | 73% | moderate |
| February Weather | -4°C (25°F) | 24 mm (0.9 inches) | 80% | moderate |
| March Weather | 3°C (38°F) | 63 mm (2.5 inches) | 64% | high |
| April Weather | 7°C (44°F) | 49 mm (1.9 inches) | 64% | very high |
| May Weather | 13°C (55°F) | 136 mm (5.4 inches) | 76% | very high |
| June Weather | 21°C (70°F) | 56 mm (2.2 inches) | 79% | extreme |
| July Weather | 23°C (74°F) | 63 mm (2.5 inches) | 77% | extreme |
| August Weather | 21°C (71°F) | 58 mm (2.3 inches) | 79% | very high |
| September Weather | 18°C (65°F) | 46 mm (1.8 inches) | 70% | very high |
| October Weather | 8°C (46°F) | 36 mm (1.4 inches) | 64% | high |
| November Weather | 3°C (38°F) | 22 mm (0.9 inches) | 75% | moderate |
| December Weather | -1°C (30°F) | 21 mm (0.8 inches) | 78% | moderate |