Click on a day for an hourly weather forecast
The temperatures in Rio Negro in September are quite cold with temperatures between 8°C and 19°C, warm clothes are a must.
You can expect about 3 to 8 days of rain in Rio Negro 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 Rio Negro in September 2025.
If you’re planning to visit Rio Negro in the near future, we highly recommend that you review the 14 day weather forecast for Rio Negro before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 33° / 17° | 3 | 28 | 0 | 93 mm | Good | Rio Negro in January |
| February | 31° / 16° | 3 | 25 | 0 | 69 mm | Good | Rio Negro in February |
| March | 28° / 14° | 4 | 28 | 0 | 82 mm | Perfect | Rio Negro in March |
| April | 23° / 12° | 3 | 27 | 0 | 83 mm | Perfect | Rio Negro in April |
| May | 18° / 9° | 3 | 28 | 0 | 62 mm | Good | Rio Negro in May |
| June | 14° / 7° | 2 | 28 | 0 | 27 mm | Good | Rio Negro in June |
| July | 14° / 5° | 2 | 29 | 0 | 34 mm | Good | Rio Negro in July |
| August | 17° / 7° | 2 | 29 | 0 | 44 mm | Good | Rio Negro in August |
| September | 19° / 8° | 4 | 26 | 0 | 81 mm | Good | Rio Negro in September |
| October | 22° / 10° | 5 | 26 | 0 | 120 mm | Good | Rio Negro in October |
| November | 27° / 13° | 5 | 25 | 0 | 113 mm | Perfect | Rio Negro in November |
| December | 31° / 16° | 4 | 27 | 0 | 95 mm | Good | Rio Negro in December |