September weather in Lake Forest, CA
The average temperature in Lake Forest in September is 75.3°F (61.7°F–88.8°F). Average precipitation: 0.10 inches.
September is a fall month in Lake Forest, and is warmer than the annual average of 66.7°F. Daily temperatures swing about 27.1°F between overnight low and afternoon high. Expect about 0 days with precipitation. Daylight averages about 12h 12m. For travel, September is hot.
Avg High
88.8°F
Avg Low
61.7°F
Precipitation
0.10 in
Daylight
12h 12m
September records in Lake Forest
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 104.0°F (2007) | 52.0°F (2010) | 0.00 in (2003) |
| September 2 | 107.1°F (2007) | 51.1°F (2010) | 0.00 in (2003) |
| September 3 | 106.0°F (2007) | 50.0°F (2010) | 0.00 in (2003) |
| September 4 | 104.0°F (2004) | 50.0°F (2011) | 0.00 in (2003) |
| September 5 | 105.1°F (2004) | 52.0°F (2010) | 0.00 in (2003) |
| September 6 | 111.9°F (2024) | 53.1°F (2010) | 0.00 in (2003) |
| September 7 | 108.0°F (2024) | 55.0°F (2005) | 0.00 in (2003) |
| September 8 | 109.9°F (2024) | 52.0°F (2020) | 0.00 in (2003) |
| September 9 | 105.1°F (2024) | 53.1°F (2010) | 0.15 in (2015) |
| September 10 | 100.0°F (2015) | 50.0°F (2010) | 0.20 in (2011) |
| September 11 | 99.0°F (2015) | 51.1°F (2010) | 0.00 in (2003) |
| September 12 | 98.1°F (2014) | 51.1°F (2011) | 0.09 in (2023) |
| September 13 | 105.1°F (2014) | 51.1°F (2010) | 0.00 in (2003) |
| September 14 | 108.0°F (2012) | 51.1°F (2010) | 0.00 in (2003) |
| September 15 | 107.1°F (2012) | 50.0°F (2010) | 1.70 in (2015) |
| September 16 | 106.0°F (2014) | 50.0°F (2010) | 0.05 in (2015) |
| September 17 | 102.0°F (2014) | 50.0°F (2010) | 0.00 in (2003) |
| September 18 | 95.0°F (2006) | 48.0°F (2010) | 0.10 in (2025) |
| September 19 | 93.0°F (2015) | 48.0°F (2006) | 0.00 in (2003) |
| September 20 | 102.9°F (2015) | 42.1°F (2006) | 0.12 in (2007) |
| September 21 | 100.0°F (2021) | 50.0°F (2007) | 0.00 in (2003) |
| September 22 | 100.0°F (2012) | 51.1°F (2007) | 0.00 in (2003) |
| September 23 | 104.0°F (2009) | 50.0°F (2007) | 0.30 in (2007) |
| September 24 | 102.0°F (2009) | 52.0°F (2010) | 0.35 in (2021) |
| September 25 | 102.9°F (2016) | 51.1°F (2023) | 0.00 in (2003) |
| September 26 | 108.0°F (2010) | 52.0°F (2023) | 0.00 in (2003) |
| September 27 | 113.0°F (2010) | 53.1°F (2011) | 0.00 in (2003) |
| September 28 | 106.0°F (2010) | 53.1°F (2006) | 0.00 in (2003) |
| September 29 | 100.9°F (2005) | 52.0°F (2011) | 0.05 in (2008) |
| September 30 | 104.0°F (2020) | 51.1°F (2013) | 0.09 in (2023) |