Click on a day for an hourly weather forecast
The temperatures in Brentwood in September are comfortable with low of 19°C and and high up to 23°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 | 3° / -1° | 6 | 18 | 7 | 109 mm | Awful | Brentwood in January |
| February | 4° / -1° | 6 | 15 | 7 | 126 mm | Awful | Brentwood in February |
| March | 7° / 3° | 6 | 21 | 4 | 138 mm | Bad | Brentwood in March |
| April | 12° / 7° | 7 | 23 | 0 | 129 mm | Bad | Brentwood in April |
| May | 17° / 13° | 7 | 24 | 0 | 147 mm | Ok | Brentwood in May |
| June | 22° / 18° | 7 | 23 | 0 | 145 mm | Ok | Brentwood in June |
| July | 26° / 22° | 8 | 24 | 0 | 193 mm | Good | Brentwood in July |
| August | 26° / 22° | 6 | 25 | 0 | 183 mm | Perfect | Brentwood in August |
| September | 23° / 19° | 6 | 24 | 0 | 134 mm | Perfect | Brentwood in September |
| October | 17° / 14° | 6 | 25 | 0 | 154 mm | Good | Brentwood in October |
| November | 11° / 8° | 5 | 24 | 1 | 88 mm | Ok | Brentwood in November |
| December | 7° / 3° | 7 | 20 | 4 | 156 mm | Awful | Brentwood in December |