Click on a day for an hourly weather forecast
The temperatures in Brentwood in September are usually low and can range between 12°C and 20°C.
You can expect about 3 to 8 days of rain in Brentwood 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 Brentwood in September 2025.
If you’re planning to visit Brentwood in the near future, we highly recommend that you review the 14 day weather forecast for Brentwood before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 7° / 2° | 8 | 19 | 4 | 75 mm | Awful | Brentwood in January |
| February | 8° / 3° | 8 | 16 | 4 | 70 mm | Awful | Brentwood in February |
| March | 11° / 4° | 6 | 24 | 1 | 58 mm | Ok | Brentwood in March |
| April | 14° / 6° | 4 | 25 | 1 | 45 mm | Good | Brentwood in April |
| May | 17° / 8° | 5 | 26 | 0 | 60 mm | Good | Brentwood in May |
| June | 20° / 11° | 5 | 25 | 0 | 80 mm | Good | Brentwood in June |
| July | 22° / 14° | 5 | 26 | 0 | 68 mm | Good | Brentwood in July |
| August | 22° / 14° | 5 | 26 | 0 | 70 mm | Good | Brentwood in August |
| September | 20° / 12° | 3 | 27 | 0 | 46 mm | Good | Brentwood in September |
| October | 15° / 10° | 7 | 24 | 0 | 80 mm | Ok | Brentwood in October |
| November | 11° / 6° | 6 | 23 | 0 | 68 mm | Ok | Brentwood in November |
| December | 8° / 4° | 7 | 21 | 2 | 88 mm | Awful | Brentwood in December |