Climate averages 1991–2020
Rennes weather
in September.
A mild, moderately wet month: the 4th warmest and the 3rd driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a mild month in Rennes: daytime highs average 20.5°C and nights cool to about 12.2°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 49 mm of rain on roughly 8 days, which makes September a moderately wet month (the 3rd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 38 min on an average September day.
The nearest other city in this atlas is Nantes (100 km away). In September its highs average 21.3°C, 0.7°C warmer than Rennes, with 49 mm of rain.
Among the 57 cities listed in France, Rennes ranks joint 34th of 57 for the warmest September highs and joint 13th of 57 for the driest September (rainfall, lowest first). The mean September high of those 57 cities is 21.3°C; Rennes is 0.7°C cooler than that mean.
From September to October, average highs fall by 4.2°C to 16.3°C, and monthly rainfall rises from 49 mm to 69 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Rennes climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 8.4°C3.3°C | 3.3°C | 64 | 11.2 | 8.89 h |
| February | 9.4°C2.9°C | 2.9°C | 53 | 9.9 | 10.210 h |
| March | 12.2°C4.6°C | 4.6°C | 52 | 10.5 | 11.912 h |
| April | 14.9°C6.3°C | 6.3°C | 58 | 11.1 | 13.614 h |
| May | 18.1°C9.5°C | 9.5°C | 63 | 10.8 | 15.215 h |
| June | 21.2°C12.4°C | 12.4°C | 53 | 9.0 | 16.016 h |
| July | 23.1°C14.2°C | 14.2°C | 46 | 7.8 | 15.616 h |
| August | 23.2°C14.3°C | 14.3°C | 46 | 8.2 | 14.314 h |
| September, selected | 20.5°C12.2°C | 12.2°C | 49 | 8.2 | 12.613 h |
| October | 16.3°C9.7°C | 9.7°C | 69 | 11.4 | 10.911 h |
| November | 11.8°C6.2°C | 6.2°C | 65 | 11.3 | 9.39 h |
| December | 8.8°C3.7°C | 3.7°C | 71 | 12.1 | 8.48 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Nantes in SeptemberFrance · 100 kmHigh 21.3°C · Low 13.0°C · 49 mm rain
- Angers in SeptemberFrance · 110 kmHigh 21.3°C · Low 12.6°C · 50 mm rain
- Saint Helier in SeptemberJersey · 124 kmHigh 17.5°C · Low 15.1°C · 77 mm rain
- Le Mans in SeptemberFrance · 140 kmHigh 20.8°C · Low 12.2°C · 51 mm rain
- Caen in SeptemberFrance · 154 kmHigh 19.8°C · Low 12.4°C · 53 mm rain
- Tours in SeptemberFrance · 195 kmHigh 21.6°C · Low 12.8°C · 49 mm rain
- Le Havre in SeptemberFrance · 202 kmHigh 19.0°C · Low 13.4°C · 78 mm rain
- Brest, France in SeptemberFrance · 210 kmHigh 17.8°C · Low 13.6°C · 52 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Rennes) is explained once on the Rennes year overview and on the Sources, method and limits page.