Last updated: June 24, 2025
In September, the average temperature in French Island, United States hovers around 18°C (65°F). Expect a minimum temperature of 4°C (39°F) and a maximum that can reach up to 33°C (92°F). With an average precipitation of 111 mm (4.4 in) over 10 days, and humidity levels around 74%, be prepared for a mix of mild weather and occasional rainfall.
In September in French Island, the average temperature is 18°C (65°F), with maximums reaching 33°C (92°F) and minimums dipping as low as 4°C (39°F). This diverse range of temperatures makes French Island an ideal destination for travelers seeking both warm sunny days and cooler evenings.
In French Island in September, the precipitation amount is 111 mm (4.4 in) over a span of 10 days.
In French Island in September humidity is 74%. With an average temperature of 18°C (65°F), this humidity feels like a warm, sticky embrace that can make even short walks feel laborious, leading travelers to seek shade and refreshment more often.
In French Island 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 French Island.
UV Risk Categories
Weather in French Island varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in French Island, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -7°C (20°F) | 37 mm (1.4 inches) | 84% | low |
| February Weather | -6°C (21°F) | 51 mm (2.0 inches) | 85% | moderate |
| March Weather | 2°C (35°F) | 58 mm (2.3 inches) | 84% | moderate |
| April Weather | 7°C (45°F) | 86 mm (3.4 inches) | 83% | very high |
| May Weather | 15°C (60°F) | 141 mm (5.5 inches) | 75% | very high |
| June Weather | 21°C (71°F) | 132 mm (5.2 inches) | 79% | very high |
| July Weather | 23°C (74°F) | 105 mm (4.1 inches) | 75% | very high |
| August Weather | 21°C (71°F) | 114 mm (4.5 inches) | 69% | very high |
| September Weather | 18°C (65°F) | 111 mm (4.4 inches) | 74% | very high |
| October Weather | 10°C (50°F) | 122 mm (4.8 inches) | 79% | moderate |
| November Weather | 2°C (35°F) | 52 mm (2.1 inches) | 88% | moderate |
| December Weather | -3°C (27°F) | 42 mm (1.7 inches) | 82% | low |