Weather on August 20
Rialto, CA
55 Years of Data
Avg High
92°F
Avg Low
63°F
Warmest
1982
88°F avg
Coldest
1989
68°F avg
About This Date
August 20th in Rialto, CA typically brings hot summer weather, with average highs around 92°F and lows near 63°F — a 29°F daily swing. Over 48 years of records, the warmest August 20th was in 1982 (88°F average), while the coldest was 1989 (68°F) — a 20°F range across recorded history. Rain or other precipitation has occurred on about 2% of August 20th dates historically.
Planning for August 20th in Rialto, CA? Stay hydrated and seek shade during peak afternoon hours.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 102° | 67° | 84° | — | — |
| 2017 | 89° | 59° | 74° | — | — |
| 2016 | 90° | 67° | 78° | — | — |
| 2015 | 86° | 60° | 73° | — | — |
| 2014 | 80° | 59° | 70° | — | — |
| 2013 | 94° | 68° | 81° | — | — |
| 2012 | 94° | 70° | 82° | — | — |
| 2011 | 84° | 57° | 71° | — | — |
| 2010 | 94° | 67° | 80° | — | — |
| 2009 | 93° | 62° | 78° | — | — |
| 2008 | 87° | 62° | 75° | — | — |
| 2007 | 96° | 68° | 82° | — | — |
| 2006 | 93° | 59° | 76° | — | — |
| 2005 | 98° | 63° | 80° | — | — |
| 2004 | 88° | 59° | 73° | — | — |
| 2003 | 97° | 71° | 84° | — | — |
| 2002 | 82° | 59° | 71° | — | — |
| 2001 | 91° | 63° | 77° | — | — |
| 2000 | 93° | 60° | 77° | — | — |
| 1999 | 100° | 69° | 85° | — | — |
| 1998 | 95° | 61° | 78° | — | — |
| 1997 | 94° | 64° | 79° | — | — |
| 1996 | 96° | 61° | 78° | — | — |
| 1995 | 96° | 67° | 81° | — | — |
| 1994 | 95° | 69° | 82° | — | — |
| 1993 | 91° | 59° | 75° | — | — |
| 1992 | 101° | 73° | 87° | — | — |
| 1991 | 92° | 59° | 75° | — | — |
| 1990 | 84° | 59° | 72° | — | — |
| 1989coldest | 79° | 57° | 68° | — | — |
| 1988 | 88° | 60° | 74° | — | — |
| 1987 | 92° | 62° | 77° | — | — |
| 1986 | 103° | 71° | 87° | — | — |
| 1985 | 91° | 59° | 75° | — | — |
| 1984 | 90° | 70° | 80° | — | — |
| 1983 | 79° | 66° | 72° | 0.08" | — |
| 1982warmest | 108° | 68° | 88° | — | — |
| 1981 | 101° | 63° | 82° | — | — |
| 1980 | 90° | 57° | 73° | — | — |
| 1979 | 87° | 66° | 77° | — | — |
| 1978 | 90° | 70° | 80° | — | — |
| 1977 | 100° | 69° | 85° | — | — |
| 1976 | 90° | 59° | 74° | — | — |
| 1975 | 86° | 57° | 72° | — | — |
| 1974 | 88° | 59° | 73° | — | — |
| 1973 | 98° | 70° | 84° | — | — |
| 1972 | 95° | 55° | 75° | — | — |
| 1971 | 97° | 62° | 79° | — | — |
48 years of data from FONTANA 5 N