August weather in Grafton, IL
The average temperature in Grafton in August is 76.9°F (66.0°F–87.8°F). Average precipitation: 3.68 inches.
August is a summer month in Grafton, and is warmer than the annual average of 56.1°F. Daily temperatures swing about 21.8°F between overnight low and afternoon high. Expect about 9 days with precipitation. Daylight averages about 13h 32m. For travel, August is a comfortable month to visit.
Avg High
87.8°F
Avg Low
66.0°F
Precipitation
3.68 in
Daylight
13h 32m
August records in Grafton
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| August 1 | 102.0°F (2002) | 55.0°F (2018) | 0.68 in (2024) |
| August 2 | 102.0°F (2011) | 57.0°F (2014) | 0.89 in (2003) |
| August 3 | 100.9°F (2010) | 57.0°F (2009) | 3.44 in (2022) |
| August 4 | 100.0°F (2010) | 57.9°F (2017) | 1.24 in (2004) |
| August 5 | 99.0°F (2002) | 54.0°F (2017) | 2.32 in (2015) |
| August 6 | 99.0°F (2018) | 52.0°F (2004) | 0.59 in (2002) |
| August 7 | 100.0°F (2007) | 54.0°F (2004) | 3.57 in (2014) |
| August 8 | 100.0°F (2007) | 55.9°F (1997) | 1.49 in (1999) |
| August 9 | 98.1°F (2001) | 55.9°F (2017) | 1.12 in (2001) |
| August 10 | 100.0°F (2005) | -0.8°F (2008) | 3.34 in (2006) |
| August 11 | 98.1°F (2007) | 54.0°F (2004) | 1.55 in (2002) |
| August 12 | 102.9°F (2007) | 48.9°F (2004) | 1.01 in (2021) |
| August 13 | 100.0°F (2010) | 48.0°F (2004) | 0.90 in (2005) |
| August 14 | 100.9°F (2007) | 48.0°F (2004) | 0.75 in (2010) |
| August 15 | 102.9°F (2007) | 48.0°F (2004) | 0.56 in (2016) |
| August 16 | 97.0°F (1997) | 51.1°F (2004) | 1.39 in (2017) |
| August 17 | 100.0°F (2000) | 55.9°F (2001) | 3.04 in (2009) |
| August 18 | 98.1°F (2025) | 54.0°F (2012) | 1.18 in (2006) |
| August 19 | 97.0°F (2005) | 55.0°F (2008) | 0.66 in (2015) |
| August 20 | 96.1°F (2003) | 53.1°F (2012) | 2.71 in (2010) |
| August 21 | 100.9°F (2003) | 55.0°F (1997) | 1.63 in (2008) |
| August 22 | 98.1°F (2001) | 51.1°F (2024) | 1.74 in (2015) |
| August 23 | 98.1°F (2007) | 52.0°F (1997) | 1.51 in (2021) |
| August 24 | 100.0°F (2023) | 53.1°F (2015) | 1.80 in (2018) |
| August 25 | 100.9°F (2023) | 53.1°F (2015) | 1.12 in (2004) |
| August 26 | 99.0°F (2003) | 48.9°F (2025) | 1.49 in (2023) |
| August 27 | 100.0°F (2024) | 50.0°F (2025) | 0.72 in (2016) |
| August 28 | 99.0°F (2007) | 54.0°F (2025) | 1.00 in (2014) |
| August 29 | 97.0°F (2000) | 55.9°F (2004) | 0.72 in (2024) |
| August 30 | 99.0°F (2013) | 54.0°F (2004) | 0.59 in (2001) |
| August 31 | 100.9°F (2011) | 53.1°F (2023) | 2.26 in (2012) |