September weather forecastBrest, France

September

Weather in September

September, the first month of the autumn in Brest, is also an enjoyable month, with an average temperature ranging between min 11.6°C (52.9°F) and max 19.1°C (66.4°F).

Temperature

The transition into September notes an average high-temperature of a refreshing 19.1°C (66.4°F), revealing a mild distinction from the 20.8°C (69.4°F) in August. Brest's nighttime temperature in September drops to an average of 11.6°C (52.9°F).

Humidity

The average relative humidity in September is 85%.

Rainfall

In Brest, France, in September, it is raining for 10.1 days, with typically 83mm (3.27") of accumulated precipitation. Throughout the year, there are 159 rainfall days, and 1210mm (47.64") of precipitation is accumulated.

Snowfall

June through October are months without snowfall in Brest.

Sea temperature

In Brest, the average seawater temperature in September is 16.6°C (61.9°F).
Note: For swimming, a surface water temperature of 16.6°C (61.9°F) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 21°C (69.8°F).

Daylight

In September, the average length of the day is 12h and 35min.
On the first day of the month, sunrise is at 07:36 and sunset at 20:59. On the last day of September, sunrise is at 08:16 and sunset at 19:58 CEST.

Sunshine

In Brest, the average sunshine in September is 5.3h.

UV index

The average daily maximum UV index in September in Brest is 4. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV radiation for the ordinary person.
Note: The maximum UV index of 4 during September translates into these guidelines:
Be cautious. Those with fair skin can be subjected to burns in fewer than 30 minutes. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Employ a hat with a wide brim for robust protection, cutting UV exposure by half.

Updated: Feb 8, 2024
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

An average high-temperature, in September, in Brest, is 19.1°C (66.4°F) and the average low-temperature is 11.6°C (52.9°F).

In September, the average relative humidity is 85%.

In Brest, France, in September, it is raining for 10.1 days, with typically 83mm (3.27") of accumulated precipitation.

June through October are months without snowfall.

In Brest, in September, the average water temperature is 16.6°C (61.9°F). For swimming, a surface water temperature of 16.6°C (61.9°F) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 21°C (69.8°F).

In Brest, the average day length in September is 12h and 35min.

On the first day of September, sunrise is at 07:36 and sunset at 20:59. On the last day of the month, sunrise is at 08:16 and sunset at 19:58 CEST.

In Brest, France, the average sunshine duration in September is 5.3h.

The average daily maximum UV index in September in Brest, France, is 4. A UV Index reading of 3 to 5 represents a moderate vulnerability from unprotected exposure to UV radiation.

Today

Tomorrow

Long-term

Year J F M A M J J A September O N D

Aug

September

Oct

Average high temperature

20.8°C

19.1°C

15.7°C

Average low temperature

Average humidity

Average rainfall

Average rainfall days

9.6

10.1

15.7

Average snowfall days

Average sea temperature

Average daylight

Average sunshine

Average UV index

Average temperature in September
Brest, France

Average high temperature in September: 19.1°C

The warmest month (with the highest average high temperature) is August (20.8°C).
The month with the lowest average high temperature is January (9.3°C).

Average low temperature in September: 11.6°C

The months with the highest average low temperature are July and August (13.2°C).
The coldest month (with the lowest average low temperature) is February (4.1°C).

Average humidity in September
Brest, France

Average humidity in September: 85%

The months with the highest relative humidity are January, October and December (86%).
The months with the lowest relative humidity are April and May (81%).

Average rainfall in September
Brest, France

Average rainfall in September: 83.3mm

The wettest month (with the highest rainfall) is December (147.8mm).
The driest month (with the least rainfall) is June (59.8mm).

Average rainfall days in September
Brest, France

Average rainfall days in September: 10.1 days

The month with the highest number of rainy days is January (17.7 days).
The month with the least rainy days is June (8.6 days).

Average snowfall days in September
Brest, France

Average snowfall days in September: 0 days

The month with the highest number of snowfall days is February (2.5 days).
The months with the least snowfall days are June, July, August, September and October (0 days).

Average sea temperature in September
Brest, France

Average sea temperature in September: 16.6°C

The best month for swimming (with the highest average sea temperature) is August (16.9°C).
The coldest month (with the lowest average sea temperature) is March (10.2°C).

Average daylight in September /
Average sunshine in September
Brest, France

Average daylight in September: 12h and 36min

The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 24min).

Average sunshine in September: 5h and 18min

The month with the most sunshine is June (Average sunshine: 6h and 24min).
The month with the least sunshine is January (Average sunshine: 2h and 0min).

Average UV index in September
Brest, France

Average UV index in September: 4

The months with the highest UV index are June and July (UV index 7).
The months with the lowest UV index are January, November and December (UV index 1).