Last updated: August 23, 2025
In Grande-Synthe, France, the average temperature in September hovers around 16°C (61°F), with minimums dipping to 5°C (42°F) and maximums reaching 30°C (86°F). Expect about 46 mm (1.8 in) of precipitation spread over 9 days, and be prepared for a relatively high average humidity of 80%.
In September in Grande-Synthe, the average temperature is 16°C (61°F). The maximum can reach 30°C (86°F), and the minimum can be as low as 5°C (42°F). This mild climate makes Grande-Synthe a pleasant destination for travelers seeking both warm days and cooler evenings.
In Grande-Synthe in September, the precipitation amount is 46 mm (1.8 in) over the course of 9 days.
In Grande-Synthe in September, humidity is 80%. With an average temperature of 16°C (61°F), this humidity feels like a warm blanket wrapped around you, making sightseeing a sweat-inducing challenge but also lending a lush vibrancy to the surroundings that can enhance your travel experience.
In Grande-Synthe in September, the maximum UV index reaches 5, which corresponds to a moderate Exposure Category. Under these conditions, the estimated time to burn is approximately 30 minutes. For more details, you can check the Hourly UV Index in Grande-Synthe.
UV Risk Categories
Weather in Grande-Synthe varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Grande-Synthe, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 5°C (42°F) | 60 mm (2.4 inches) | 91% | low |
| February Weather | 6°C (44°F) | 54 mm (2.1 inches) | 89% | low |
| March Weather | 8°C (46°F) | 58 mm (2.3 inches) | 86% | moderate |
| April Weather | 10°C (51°F) | 32 mm (1.2 inches) | 85% | moderate |
| May Weather | 13°C (56°F) | 59 mm (2.3 inches) | 82% | high |
| June Weather | 17°C (63°F) | 64 mm (2.5 inches) | 81% | very high |
| July Weather | 19°C (66°F) | 50 mm (1.9 inches) | 76% | very high |
| August Weather | 19°C (66°F) | 71 mm (2.8 inches) | 73% | high |
| September Weather | 16°C (61°F) | 46 mm (1.8 inches) | 80% | moderate |
| October Weather | 13°C (56°F) | 80 mm (3.2 inches) | 89% | moderate |
| November Weather | 9°C (48°F) | 55 mm (2.1 inches) | 92% | low |
| December Weather | 7°C (45°F) | 93 mm (3.7 inches) | 92% | low |