Weather on April 21
Ontario, CA
55 Years of Data
About This Date
April 21st in Ontario, CA typically brings pleasant spring weather, with average highs around 76°F and lows near 50°F — a 26°F daily swing. Over 43 years of records, the warmest April 21st was in 2009 (83°F average), while the coldest was 2010 (51°F) — a 32°F range across recorded history. Rain or other precipitation has occurred on about 12% of April 21st dates historically, with the wettest April 21st recording 2.08" of rain. The last decade has been 4.9°F warmer on this date compared to 20-30 years ago.
The last decade has been 4.9°F warmer on this date compared to 20-30 years ago.
Planning for April 21st in Ontario, CA? Great weather for outdoor activities.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2026 | 70° | 53° | 61° | — | — |
| 2025 | 79° | 53° | 66° | — | — |
| 2024 | 84° | 53° | 69° | — | — |
| 2023 | 90° | 53° | 71° | — | — |
| 2022 | 72° | 49° | 60° | 0.03" | — |
| 2021 | 63° | 54° | 58° | — | — |
| 2020 | 74° | 54° | 64° | — | — |
| 2019 | 74° | 57° | 65° | — | — |
| 2018 | 90° | 50° | 70° | — | — |
| 2017 | 93° | 56° | 74° | — | — |
| 2016 | 87° | 56° | 71° | — | — |
| 2015 | 66° | 55° | 61° | — | — |
| 2014 | 88° | 57° | 72° | — | — |
| 2013 | 89° | 57° | 73° | — | — |
| 2012 | 91° | 57° | 74° | — | — |
| 2011 | 69° | 54° | 61° | — | — |
| 2010coldest | 60° | 42° | 51° | — | — |
| 2009warmest | 100° | 66° | 83° | — | — |
| 2008 | 71° | 46° | 59° | — | — |
| 2007 | 63° | 47° | 55° | — | — |
| 2006 | 73° | 55° | 64° | — | — |
| 2005 | 83° | 50° | 66° | — | — |
| 2004 | 72° | 51° | 61° | — | — |
| 2003 | 65° | 50° | 57° | — | — |
| 2002 | 82° | 45° | 63° | — | — |
| 2001 | 64° | 45° | 54° | 0.61" | — |
| 2000 | 65° | 52° | 58° | 0.03" | — |
| 1999 | 65° | 53° | 59° | — | — |
| 1998 | 95° | 50° | 73° | — | — |
| 1984 | 81° | 49° | 65° | — | — |
| 1983 | 63° | 48° | 55° | 2.08" | — |
| 1982 | 75° | 58° | 66° | — | — |
| 1981 | 78° | 44° | 61° | — | — |
| 1980 | 69° | 53° | 61° | 0.15" | — |
| 1979 | 81° | 45° | 63° | — | — |
| 1978 | 75° | 40° | 57° | — | — |
| 1977 | 80° | 46° | 63° | — | — |
| 1976 | 81° | 51° | 66° | — | — |
| 1975 | 72° | 42° | 57° | — | — |
| 1974 | 81° | 42° | 61° | — | — |
| 1973 | 75° | 43° | 59° | — | — |
| 1972 | 80° | 43° | 61° | — | — |
| 1971 | 59° | 44° | 52° | — | — |
Ontario, CA Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
Ontario, CA Monthly Precipitation
Average rainfall per month, in inches.
Ontario, 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 Ontario, CA
Ontario, CA has no months that meet our "pleasant" threshold — every season has tradeoffs.