Weather on September 20
Rancho Cucamonga, CA
55 Years of Data
Avg High
86°F
Avg Low
60°F
Warmest
2015
87°F avg
Coldest
1973
63°F avg
About This Date
September 20th in Rancho Cucamonga, CA typically brings warm fall weather, with average highs around 86°F and lows near 60°F — a 26°F daily swing. Over 41 years of records, the warmest September 20th was in 2015 (87°F average), while the coldest was 1973 (63°F) — a 24°F range across recorded history. Rain or other precipitation has occurred on about 7% of September 20th dates historically, with the wettest September 20th recording 0.74" of rain. The last decade has been 2.6°F warmer on this date compared to 20-30 years ago.
The last decade has been 2.6°F warmer on this date compared to 20-30 years ago.
Planning for September 20th in Rancho Cucamonga, CA? Stay hydrated and seek shade during peak afternoon hours.
Warming Trend
1.1°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 92° | 67° | 79° | — | — |
| 2024 | 78° | 60° | 69° | — | — |
| 2023 | 78° | 62° | 70° | 0.05" | — |
| 2022 | 86° | 60° | 73° | — | — |
| 2021 | 93° | 62° | 78° | — | — |
| 2020 | 94° | 64° | 79° | — | — |
| 2019 | 86° | 63° | 74° | — | — |
| 2018 | 90° | 62° | 76° | — | — |
| 2017 | 79° | 64° | 71° | — | — |
| 2016 | 84° | 70° | 77° | — | — |
| 2015warmest | 104° | 70° | 87° | — | — |
| 2014 | 82° | 64° | 73° | — | — |
| 2013 | 78° | 63° | 70° | — | — |
| 2012 | 101° | 65° | 83° | — | — |
| 2011 | 89° | 60° | 75° | — | — |
| 2010 | 88° | 58° | 73° | — | — |
| 2009 | 92° | 62° | 77° | — | — |
| 2008 | 84° | 60° | 72° | — | — |
| 2007 | 70° | 56° | 63° | 0.13" | — |
| 2006 | 84° | 58° | 71° | — | — |
| 2005 | 78° | 63° | 70° | 0.74" | — |
| 2004 | 77° | 55° | 66° | — | — |
| 2003 | 96° | 61° | 78° | — | — |
| 2002 | 94° | 59° | 76° | — | — |
| 2001 | 85° | 57° | 71° | — | — |
| 2000 | 85° | 63° | 74° | — | — |
| 1999 | 92° | 53° | 72° | — | — |
| 1998 | 75° | 62° | 69° | — | — |
| 1983 | 88° | 68° | 78° | — | — |
| 1982 | 90° | 51° | 70° | — | — |
| 1981 | 94° | 62° | 78° | — | — |
| 1980 | 81° | 52° | 66° | — | — |
| 1979 | 95° | 66° | 81° | — | — |
| 1978 | 86° | 50° | 68° | — | — |
| 1977 | 77° | 50° | 64° | — | — |
| 1976 | 75° | 60° | 68° | — | — |
| 1975 | 88° | 59° | 73° | — | — |
| 1974 | 90° | 55° | 72° | — | — |
| 1973coldest | 77° | 48° | 63° | — | — |
| 1972 | 91° | 50° | 71° | — | — |
| 1971 | 83° | 53° | 68° | — | — |
41 years of data from ONTARIO INTL AP