Weather on October 21
Ontario, CA
55 Years of Data
Avg High
80°F
Avg Low
54°F
Warmest
2003
82°F avg
Coldest
1979
56°F avg
About This Date
October 21st in Ontario, CA typically brings warm fall weather, with average highs around 80°F and lows near 54°F — a 26°F daily swing. Over 41 years of records, the warmest October 21st was in 2003 (82°F average), while the coldest was 1979 (56°F) — a 26°F range across recorded history. Rain or other precipitation has occurred on about 5% of October 21st dates historically. The last decade has been 5.5°F warmer on this date compared to 20-30 years ago.
The last decade has been 5.5°F warmer on this date compared to 20-30 years ago.
Planning for October 21st in Ontario, CA? Stay hydrated and seek shade during peak afternoon hours.
Warming Trend
2.2°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 90° | 58° | 74° | — | — |
| 2024 | 89° | 57° | 73° | — | — |
| 2023 | 89° | 63° | 76° | — | — |
| 2022 | 83° | 61° | 72° | — | — |
| 2021 | 86° | 54° | 70° | — | — |
| 2020 | 79° | 62° | 70° | — | — |
| 2019 | 95° | 57° | 76° | — | — |
| 2018 | 83° | 58° | 70° | — | — |
| 2017 | 82° | 54° | 68° | — | — |
| 2016 | 94° | 56° | 75° | — | — |
| 2015 | 85° | 57° | 71° | — | — |
| 2014 | 81° | 58° | 69° | — | — |
| 2013 | 84° | 52° | 68° | — | — |
| 2012 | 73° | 62° | 68° | — | — |
| 2011 | 77° | 58° | 67° | — | — |
| 2010 | 62° | 58° | 60° | 0.08" | — |
| 2009 | 84° | 53° | 69° | — | — |
| 2008 | 92° | 53° | 72° | — | — |
| 2007 | 83° | 54° | 68° | — | — |
| 2006 | 93° | 53° | 73° | — | — |
| 2005 | 76° | 57° | 66° | — | — |
| 2004 | 66° | 50° | 58° | 0.03" | — |
| 2003warmest | 101° | 63° | 82° | — | — |
| 2002 | 67° | 55° | 61° | — | — |
| 2001 | 73° | 57° | 65° | — | — |
| 2000 | 68° | 58° | 63° | — | — |
| 1999 | 94° | 54° | 74° | — | — |
| 1998 | 80° | 51° | 66° | — | — |
| 1983 | 86° | 48° | 67° | — | — |
| 1982 | 81° | 50° | 65° | — | — |
| 1981 | 84° | 47° | 65° | — | — |
| 1980 | 87° | 50° | 69° | — | — |
| 1979coldest | 67° | 45° | 56° | — | — |
| 1978 | 73° | 58° | 65° | — | — |
| 1977 | 69° | 53° | 61° | — | — |
| 1976 | 75° | 59° | 67° | — | — |
| 1975 | 67° | 48° | 57° | — | — |
| 1974 | 67° | 55° | 61° | — | — |
| 1973 | 71° | 47° | 59° | — | — |
| 1972 | 68° | 46° | 57° | — | — |
| 1971 | 79° | 41° | 60° | — | — |
41 years of data from ONTARIO INTL AP