Weather on August 21
Fontana, CA
55 Years of Data
Avg High
93°F
Avg Low
63°F
Warmest
1982
90°F avg
Coldest
1975
69°F avg
About This Date
August 21st in Fontana, CA typically brings hot summer weather, with average highs around 93°F and lows near 63°F — a 30°F daily swing. Over 55 years of records, the warmest August 21st was in 1982 (90°F average), while the coldest was 1975 (69°F) — a 21°F range across recorded history. Rain or other precipitation has occurred on about 2% of August 21st dates historically, with the wettest August 21st recording 0.58" of rain. The last decade has been 3.0°F warmer on this date compared to 20-30 years ago.
The last decade has been 3.0°F warmer on this date compared to 20-30 years ago.
Planning for August 21st in Fontana, CA? Stay hydrated and seek shade during peak afternoon hours.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 103° | 74° | 88° | — | — |
| 2024 | 99° | 69° | 84° | — | — |
| 2023 | 83° | 62° | 72° | 0.58" | — |
| 2022 | 87° | 65° | 76° | — | — |
| 2021 | 77° | 65° | 71° | — | — |
| 2020 | 103° | 74° | 88° | — | — |
| 2019 | 98° | 66° | 82° | — | — |
| 2018 | 91° | 67° | 79° | — | — |
| 2017 | 90° | 64° | 77° | — | — |
| 2016 | 93° | 64° | 79° | — | — |
| 2015 | 88° | 66° | 77° | — | — |
| 2014 | 92° | 64° | 78° | — | — |
| 2013 | 100° | 66° | 83° | — | — |
| 2012 | 93° | 70° | 81° | — | — |
| 2011 | 87° | 57° | 72° | — | — |
| 2010 | 97° | 66° | 81° | — | — |
| 2009 | 86° | 64° | 75° | — | — |
| 2008 | 90° | 64° | 77° | — | — |
| 2007 | 99° | 68° | 83° | — | — |
| 2006 | 94° | 60° | 77° | — | — |
| 2005 | 94° | 61° | 77° | — | — |
| 2004 | 82° | 61° | 71° | — | — |
| 2003 | 89° | 66° | 78° | — | — |
| 2002 | 80° | 60° | 70° | — | — |
| 2001 | 84° | 60° | 72° | — | — |
| 2000 | 90° | 61° | 75° | — | — |
| 1999 | 98° | 59° | 79° | — | — |
| 1998 | 100° | 63° | 81° | — | — |
| 1997 | 100° | 66° | 83° | — | — |
| 1996 | 100° | 60° | 80° | — | — |
| 1995 | 98° | 70° | 84° | — | — |
| 1994 | 93° | 55° | 74° | — | — |
| 1993 | 91° | 58° | 74° | — | — |
| 1992 | 101° | 69° | 85° | — | — |
| 1991 | 100° | 62° | 81° | — | — |
| 1990 | 90° | 59° | 74° | — | — |
| 1989 | 83° | 60° | 71° | — | — |
| 1988 | 88° | 62° | 75° | — | — |
| 1987 | 93° | 60° | 77° | — | — |
| 1986 | 102° | 66° | 84° | — | — |
| 1985 | 95° | 57° | 76° | — | — |
| 1984 | 98° | 66° | 82° | — | — |
| 1983 | 80° | 62° | 71° | — | — |
| 1982warmest | 108° | 72° | 90° | — | — |
| 1981 | 104° | 62° | 83° | — | — |
| 1980 | 90° | 54° | 72° | — | — |
| 1979 | 89° | 56° | 72° | — | — |
| 1978 | — | 56° | — | — | — |
| 1977 | 94° | 67° | 80° | — | — |
| 1976 | 95° | 65° | 80° | — | — |
| 1975coldest | 83° | 56° | 69° | — | — |
| 1974 | 87° | 58° | 72° | — | — |
| 1973 | 93° | 69° | 81° | — | — |
| 1972 | 102° | 66° | 84° | — | — |
| 1971 | 93° | 66° | 80° | — | — |
55 years of data from FONTANA KAISER