Weather on December 20
Rialto, CA
55 Years of Data
Avg High
63°F
Avg Low
43°F
Warmest
1999
68°F avg
Coldest
1990
37°F avg
About This Date
December 20th in Rialto, CA typically brings mild winter weather, with average highs around 63°F and lows near 43°F. Over 47 years of records, the warmest December 20th was in 1999 (68°F average), while the coldest was 1990 (37°F) — a 31°F range across recorded history. Rain or other precipitation has occurred on about 6% of December 20th dates historically, with the wettest December 20th recording 1.27" of rain.
Planning for December 20th in Rialto, CA? Great weather for outdoor activities.
Cooling Trend
0.8°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 73° | 45° | 59° | — | — |
| 2016 | 63° | 50° | 56° | — | — |
| 2015 | 53° | 41° | 47° | — | — |
| 2014 | 56° | 45° | 50° | — | — |
| 2013 | 58° | 40° | 49° | — | — |
| 2012 | 52° | 39° | 45° | — | — |
| 2011 | 60° | 44° | 52° | — | — |
| 2010 | 54° | 48° | 51° | — | — |
| 2009 | 66° | 50° | 58° | — | — |
| 2008 | 52° | 38° | 45° | — | — |
| 2007 | 51° | 44° | 48° | — | — |
| 2006 | 54° | 36° | 45° | — | — |
| 2005 | 67° | 54° | 60° | — | — |
| 2004 | 74° | 46° | 60° | — | — |
| 2003 | 60° | 50° | 55° | — | — |
| 2002 | 45° | 40° | 42° | — | — |
| 2001 | 57° | 41° | 49° | — | — |
| 2000 | 80° | 49° | 64° | — | — |
| 1999warmest | 73° | 63° | 68° | — | — |
| 1998 | 48° | 38° | 43° | — | — |
| 1997 | 67° | 41° | 54° | — | — |
| 1996 | 73° | 45° | 59° | — | — |
| 1995 | 64° | 38° | 51° | — | — |
| 1994 | 73° | 56° | 64° | — | — |
| 1993 | 57° | 46° | 52° | — | — |
| 1992 | 51° | 36° | 43° | — | — |
| 1991 | 58° | 48° | 53° | — | — |
| 1990coldest | 47° | 28° | 37° | — | — |
| 1989 | 65° | 36° | 50° | — | — |
| 1988 | 55° | 39° | 47° | — | — |
| 1987 | 60° | 36° | 48° | — | — |
| 1986 | 62° | 50° | 56° | 0.33" | — |
| 1985 | 78° | 43° | 60° | — | — |
| 1984 | 64° | 42° | 53° | 1.27" | — |
| 1983 | 60° | 50° | 55° | — | — |
| 1982 | 78° | 40° | 59° | — | — |
| 1981 | 69° | 44° | 57° | — | — |
| 1980 | 81° | 45° | 63° | — | — |
| 1979 | 68° | 40° | 54° | — | — |
| 1978 | 59° | 32° | 46° | — | — |
| 1977 | 62° | 37° | 50° | — | — |
| 1976 | 74° | 39° | 56° | — | — |
| 1975 | 64° | 53° | 59° | 0.43" | — |
| 1974 | 76° | 39° | 57° | — | — |
| 1973 | 73° | 36° | 54° | — | — |
| 1972 | 80° | 50° | 65° | — | — |
| 1971 | 62° | 34° | 48° | — | — |
47 years of data from FONTANA 5 N