Click on a day for an hourly weather forecast
The temperatures in Oyonnax in September are comfortable with low of 10°C and and high up to 22°C.
You can expect about 3 to 8 days of rain in Oyonnax during the month of September. It’s a good idea to bring along your umbrella so that you don’t get caught in poor weather.
Our weather forecast can give you a great sense of what weather to expect in Oyonnax in September 2026.
If you’re planning to visit Oyonnax in the near future, we highly recommend that you review the 14 day weather forecast for Oyonnax before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 5° / -1° | 10 | 14 | 7 | 156 mm | Awful | Oyonnax in January |
| February | 7° / 0° | 9 | 14 | 6 | 131 mm | Awful | Oyonnax in February |
| March | 12° / 2° | 9 | 21 | 2 | 126 mm | Awful | Oyonnax in March |
| April | 16° / 5° | 7 | 23 | 0 | 131 mm | Ok | Oyonnax in April |
| May | 19° / 7° | 10 | 21 | 0 | 199 mm | Ok | Oyonnax in May |
| June | 24° / 11° | 10 | 20 | 0 | 194 mm | Good | Oyonnax in June |
| July | 26° / 13° | 7 | 24 | 0 | 153 mm | Good | Oyonnax in July |
| August | 26° / 13° | 6 | 25 | 0 | 157 mm | Perfect | Oyonnax in August |
| September | 22° / 10° | 5 | 25 | 0 | 119 mm | Good | Oyonnax in September |
| October | 16° / 7° | 7 | 24 | 0 | 143 mm | Ok | Oyonnax in October |
| November | 10° / 3° | 9 | 19 | 2 | 178 mm | Awful | Oyonnax in November |
| December | 7° / 1° | 11 | 15 | 5 | 188 mm | Awful | Oyonnax in December |