August weather in Alton, IL
The average temperature in Alton in August is 76.6°F (67.3°F–86.0°F). Average precipitation: 3.30 inches.
August is a summer month in Alton, and is warmer than the annual average of 55.7°F. Daily temperatures swing about 18.7°F between overnight low and afternoon high. Expect about 7 days with precipitation. Daylight averages about 13h 31m. For travel, August is a comfortable month to visit.
Avg High
86.0°F
Avg Low
67.3°F
Precipitation
3.30 in
Daylight
13h 31m
August records in Alton
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| August 1 | 106.0°F (1953) | 57.0°F (1971) | 1.89 in (1985) |
| August 2 | 104.0°F (1953) | 55.9°F (1985) | 1.90 in (1966) |
| August 3 | 104.0°F (1953) | 54.0°F (1950) | 1.35 in (1946) |
| August 4 | 102.9°F (1987) | 55.9°F (1950) | 1.75 in (2022) |
| August 5 | 100.9°F (1947) | 54.0°F (1948) | 1.40 in (1920) |
| August 6 | 102.9°F (1947) | 52.0°F (1948) | 2.80 in (1959) |
| August 7 | 104.0°F (1947) | 54.0°F (1994) | 1.71 in (1995) |
| August 8 | 98.1°F (1944) | 54.0°F (1976) | 1.36 in (1982) |
| August 9 | 102.0°F (1944) | 55.0°F (1976) | 1.93 in (2021) |
| August 10 | 102.0°F (1980) | 55.9°F (1948) | 3.16 in (1961) |
| August 11 | 100.0°F (1944) | 55.0°F (1982) | 1.43 in (2006) |
| August 12 | 99.0°F (2010) | 55.0°F (1967) | 2.70 in (2002) |
| August 13 | 100.9°F (2007) | 53.1°F (1964) | 1.85 in (2019) |
| August 14 | 100.0°F (2010) | 55.0°F (2004) | 1.25 in (2005) |
| August 15 | 99.0°F (1995) | 54.0°F (1992) | 4.00 in (1946) |
| August 16 | 102.0°F (2007) | 54.0°F (1992) | 4.31 in (1946) |
| August 17 | 100.9°F (1988) | 53.1°F (1996) | 1.20 in (2017) |
| August 18 | 100.9°F (1988) | 54.0°F (1963) | 1.90 in (2009) |
| August 19 | 100.9°F (1988) | 55.0°F (1953) | 1.45 in (1963) |
| August 20 | 102.0°F (1947) | 48.0°F (1950) | 0.92 in (2002) |
| August 21 | 109.0°F (1996) | 46.9°F (1950) | 1.63 in (1964) |
| August 22 | 104.0°F (1948) | 51.1°F (1950) | 1.56 in (2017) |
| August 23 | 106.0°F (1948) | 53.1°F (1984) | 2.97 in (1983) |
| August 24 | 102.9°F (1947) | 54.0°F (1951) | 2.72 in (1977) |
| August 25 | 100.0°F (2023) | 48.9°F (2025) | 1.95 in (2018) |
| August 26 | 100.0°F (2023) | 51.1°F (2025) | 1.85 in (1975) |
| August 27 | 102.0°F (1983) | 51.1°F (1985) | 2.50 in (2023) |
| August 28 | 100.0°F (2024) | 46.9°F (1986) | 2.97 in (1974) |
| August 29 | 100.9°F (1983) | 46.0°F (1986) | 0.77 in (1991) |
| August 30 | 100.9°F (1945) | 46.9°F (1986) | 1.07 in (1975) |
| August 31 | 98.1°F (1952) | 48.0°F (1986) | 1.61 in (2001) |