Weather on May 21
Rialto, CA
55 Years of Data
About This Date
May 21st in Rialto, CA typically brings pleasant spring weather, with average highs around 79°F and lows near 54°F — a 25°F daily swing. Over 49 years of records, the warmest May 21st was in 2000 (85°F average), while the coldest was 1991 (54°F) — a 31°F range across recorded history. Rain or other precipitation has occurred on about 4% of May 21st dates historically.
Planning for May 21st in Rialto, CA? Great weather for outdoor activities.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2026 | 88° | 57° | 72° | — | — |
| 2025 | 95° | 60° | 77° | — | — |
| 2017 | 91° | 66° | 79° | — | — |
| 2016 | 64° | 50° | 57° | — | — |
| 2015 | 62° | 52° | 57° | — | — |
| 2014 | 67° | 48° | 57° | — | — |
| 2013 | 83° | 58° | 70° | — | — |
| 2012 | 92° | 65° | 78° | — | — |
| 2011 | 76° | 50° | 63° | — | — |
| 2010 | 72° | 52° | 62° | — | — |
| 2009 | 80° | 57° | 69° | — | — |
| 2008 | 71° | 54° | 62° | — | — |
| 2007 | 60° | 54° | 57° | — | — |
| 2006 | 71° | 54° | 62° | — | — |
| 2005 | 96° | 62° | 79° | — | — |
| 2004 | 63° | 53° | 58° | — | — |
| 2003 | 99° | 68° | 83° | — | — |
| 2002 | 66° | 45° | 55° | — | — |
| 2001 | 87° | 55° | 71° | — | — |
| 2000warmest | 104° | 67° | 85° | — | — |
| 1999 | 68° | 51° | 60° | — | — |
| 1998 | 71° | 48° | 60° | — | — |
| 1997 | 82° | 58° | 70° | — | — |
| 1996 | 72° | 52° | 62° | — | — |
| 1995 | 70° | 47° | 58° | — | — |
| 1994 | 86° | 47° | 66° | — | — |
| 1993 | 70° | 55° | 62° | — | — |
| 1992 | 74° | 51° | 62° | — | — |
| 1991coldest | 63° | 46° | 54° | — | — |
| 1990 | 78° | 51° | 65° | — | — |
| 1989 | 86° | 54° | 70° | — | — |
| 1988 | 97° | 58° | 77° | — | — |
| 1987 | 86° | 59° | 73° | — | — |
| 1986 | 75° | 57° | 66° | — | — |
| 1985 | 85° | 56° | 70° | — | — |
| 1984 | 86° | 57° | 72° | — | — |
| 1983 | 90° | 54° | 72° | — | — |
| 1982 | 77° | 59° | 68° | — | — |
| 1981 | 80° | 46° | 63° | — | — |
| 1980 | 70° | 55° | 62° | — | — |
| 1979 | 75° | 58° | 66° | — | — |
| 1978 | 84° | 52° | 68° | — | — |
| 1977 | 88° | 53° | 70° | — | — |
| 1976 | 79° | 53° | 66° | — | — |
| 1975 | 70° | 43° | 56° | 0.08" | — |
| 1974 | 89° | 48° | 69° | — | — |
| 1973 | 79° | 56° | 67° | — | — |
| 1972 | 72° | 42° | 57° | 0.08" | — |
| 1971 | 76° | 48° | 62° | — | — |
Rialto, CA Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
Rialto, CA Monthly Precipitation
Average rainfall and snowfall per month, in inches.
Rialto, CA Daily Temperature Calendar
Average daily high temperature for every day of the year. Each cell is the climatological mean for that calendar day across 55 years of NOAA data.
Best Time to Visit Rialto, CA
Rialto, CA has no months that meet our "pleasant" threshold — every season has tradeoffs.