September weather in Round Lake Beach, IL
The average temperature in Round Lake Beach in September is 63.9°F (54.4°F–73.4°F). Average precipitation: 3.36 inches.
September is a fall month in Round Lake Beach, and is warmer than the annual average of 48.6°F. Daily temperatures swing about 19°F between overnight low and afternoon high. Expect about 9 days with precipitation. Daylight averages about 12h 16m. For travel, September is one of the best months of the year to visit.
Avg High
73.4°F
Avg Low
54.4°F
Precipitation
3.36 in
Daylight
12h 16m
September records in Round Lake Beach
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 91.0°F (2000) | 46.9°F (1994) | 0.55 in (1989) |
| September 2 | 90.0°F (1999) | 51.1°F (1994) | 0.98 in (2002) |
| September 3 | 90.0°F (1999) | 46.0°F (1997) | 0.51 in (1991) |
| September 4 | 90.0°F (1999) | 44.1°F (1997) | 0.33 in (1988) |
| September 5 | 91.0°F (1999) | 45.0°F (1988) | 0.12 in (2004) |
| September 6 | 93.0°F (1990) | 43.0°F (1988) | 0.41 in (1989) |
| September 7 | 89.1°F (2005) | 46.9°F (1988) | 0.77 in (2001) |
| September 8 | 91.0°F (2002) | 48.0°F (1995) | 0.09 in (1992) |
| September 9 | 91.9°F (1991) | 46.0°F (1995) | 0.96 in (1992) |
| September 10 | 90.0°F (2005) | 45.0°F (1993) | 1.04 in (1986) |
| September 11 | 89.1°F (2005) | 42.1°F (1993) | 1.45 in (2000) |
| September 12 | 89.1°F (1998) | 48.0°F (1989) | 0.98 in (1991) |
| September 13 | 91.0°F (1998) | 48.0°F (1996) | 0.56 in (1989) |
| September 14 | 87.1°F (1994) | 44.1°F (1996) | 1.20 in (1998) |
| September 15 | 87.1°F (1991) | 45.0°F (1999) | 0.73 in (2004) |
| September 16 | 82.9°F (1994) | 43.0°F (2000) | 1.22 in (1992) |
| September 17 | 90.0°F (1988) | 46.0°F (1990) | 0.62 in (1992) |
| September 18 | 84.0°F (2000) | 41.0°F (1991) | 0.48 in (2001) |
| September 19 | 84.0°F (1997) | 39.0°F (1991) | 1.25 in (1997) |
| September 20 | 84.9°F (1998) | 36.0°F (1991) | 0.60 in (1992) |
| September 21 | 87.1°F (2005) | 37.9°F (1995) | 0.56 in (1990) |
| September 22 | 84.0°F (2005) | 33.1°F (1995) | 3.46 in (1986) |
| September 23 | 82.0°F (2004) | 32.0°F (1995) | 0.67 in (2001) |
| September 24 | 78.1°F (2004) | 35.1°F (1989) | 2.90 in (1986) |
| September 25 | 79.0°F (1998) | 37.0°F (2001) | 1.88 in (1993) |
| September 26 | 86.0°F (1998) | 39.0°F (1991) | 1.35 in (1986) |
| September 27 | 82.9°F (1998) | 33.1°F (1991) | 2.14 in (1999) |
| September 28 | 80.1°F (1987) | 37.0°F (1991) | 1.82 in (1999) |
| September 29 | 81.0°F (2002) | 35.1°F (1993) | 1.13 in (2002) |
| September 30 | 82.0°F (2002) | 33.1°F (1993) | 0.22 in (1995) |