Weather on August 18
Rancho Cucamonga, CA
55 Years of Data
Avg High
91°F
Avg Low
64°F
Warmest
2020
92°F avg
Coldest
1976
65°F avg
About This Date
August 18th in Rancho Cucamonga, CA typically brings hot summer weather, with average highs around 91°F and lows near 64°F — a 27°F daily swing. Over 42 years of records, the warmest August 18th was in 2020 (92°F average), while the coldest was 1976 (65°F) — a 27°F range across recorded history. Rain or other precipitation has occurred on about 5% of August 18th dates historically, with the wettest August 18th recording 1.22" of rain. The last decade has been 2.2°F warmer on this date compared to 20-30 years ago.
The last decade has been 2.2°F warmer on this date compared to 20-30 years ago.
Planning for August 18th in Rancho Cucamonga, CA? Stay hydrated and seek shade during peak afternoon hours.
Warming Trend
1.8°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 93° | 62° | 78° | — | — |
| 2024 | 94° | 63° | 78° | — | — |
| 2023 | 96° | 65° | 80° | — | — |
| 2022 | 96° | 68° | 82° | — | — |
| 2021 | 79° | 70° | 74° | — | — |
| 2020warmest | 108° | 76° | 92° | — | — |
| 2019 | 88° | 61° | 74° | — | — |
| 2018 | 94° | 69° | 81° | — | — |
| 2017 | 89° | 63° | 76° | — | — |
| 2016 | 100° | 66° | 83° | — | — |
| 2015 | 91° | 66° | 79° | — | — |
| 2014 | 98° | 67° | 82° | — | — |
| 2013 | 95° | 65° | 80° | — | — |
| 2012 | 99° | 76° | 87° | — | — |
| 2011 | 95° | 64° | 80° | — | — |
| 2010 | 98° | 72° | 85° | — | — |
| 2009 | 89° | 59° | 74° | — | — |
| 2008 | 90° | 63° | 76° | — | — |
| 2007 | 100° | 71° | 86° | — | — |
| 2006 | 92° | 62° | 77° | — | — |
| 2005 | 87° | 59° | 73° | — | — |
| 2004 | 90° | 63° | 76° | — | — |
| 2003 | 97° | 67° | 82° | — | — |
| 2002 | 81° | 64° | 72° | — | — |
| 2001 | 99° | 68° | 83° | — | — |
| 2000 | 94° | 68° | 81° | — | — |
| 1999 | 93° | 64° | 79° | — | — |
| 1998 | 88° | 62° | 75° | — | — |
| 1984 | 89° | 69° | 79° | — | — |
| 1983 | 73° | 68° | 71° | 1.22" | — |
| 1982 | 99° | 62° | 80° | — | — |
| 1981 | 89° | 64° | 77° | — | — |
| 1980 | 84° | 61° | 72° | — | — |
| 1979 | 83° | 60° | 71° | — | — |
| 1978 | 88° | 50° | 69° | — | — |
| 1977 | 80° | 65° | 72° | 0.23" | — |
| 1976coldest | 78° | 52° | 65° | — | — |
| 1975 | 81° | 51° | 66° | — | — |
| 1974 | 88° | 54° | 71° | — | — |
| 1973 | 98° | 64° | 81° | — | — |
| 1972 | 80° | 56° | 68° | — | — |
| 1971 | 91° | 61° | 76° | — | — |
42 years of data from ONTARIO INTL AP