Rancho Cucamonga Weather in August
Average highs run from 95°F on August 1 to 95°F on August 31, and lows from 65°F to 65°F. Normal precipitation for the month is 0.03 in over about 0 wet days.
August day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
August at a glance
- Average high
- 95°F
- Average low
- 65°F
- Precipitation
- 0.03 in
- Record high
- 112°FAug 31, 2017
- Record low
- 56°FAug 8, 1999
- Chance of a freeze
- 0%
- Days of 90°F or more
- 23.8
- Daylight
- 13 h 49 min to 12 h 54 min
- Cloud cover
- 16%
- Humidity
- 39%
- Dew point
- 47°F
- Wind
- 5.4 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation.
| Date | Normal high | Normal low | Record high | Record low | Chance wet |
|---|---|---|---|---|---|
| Aug 1 | 95°F | 65°F | 104°F 2017 | 58°F 2010 | 2% |
| Aug 2 | 95°F | 65°F | 104°F 2021 | 58°F 2013 | 2% |
| Aug 3 | 95°F | 65°F | 105°F 1998 | 59°F 2013 | 2% |
| Aug 4 | 95°F | 65°F | 104°F 1998 | 58°F 2002 | 2% |
| Aug 5 | 95°F | 65°F | 107°F 2024 | 58°F 2010 | 1% |
| Aug 6 | 95°F | 65°F | 107°F 2012 | 57°F 2010 | 1% |
| Aug 7 | 95°F | 65°F | 104°F 2012 | 57°F 1999 | 1% |
| Aug 8 | 95°F | 65°F | 104°F 2012 | 56°F 1999 | 1% |
| Aug 9 | 95°F | 65°F | 104°F 2012 | 56°F 2010 | 1% |
| Aug 10 | 95°F | 65°F | 104°F 2012 | 58°F 1999 | 1% |
| Aug 11 | 95°F | 65°F | 105°F 2012 | 57°F 1999 | 1% |
| Aug 12 | 95°F | 65°F | 105°F 2012 | 57°F 2010 | 1% |
| Aug 13 | 95°F | 65°F | 105°F 2012 | 59°F 2010 | 1% |
| Aug 14 | 95°F | 65°F | 105°F 2003 | 57°F 2010 | 1% |
| Aug 15 | 95°F | 65°F | 110°F 2020 | 58°F 1999 | 1% |
| Aug 16 | 95°F | 65°F | 107°F 2015 | 58°F 1999 | 1% |
| Aug 17 | 95°F | 65°F | 102°F 2023 | 58°F 2009 | 1% |
| Aug 18 | 95°F | 65°F | 108°F 2020 | 59°F 2005 | 1% |
| Aug 19 | 95°F | 65°F | 107°F 2020 | 59°F 2005 | 1% |
| Aug 20 | 95°F | 65°F | 104°F 2020 | 59°F 2005 | 1% |
| Aug 21 | 95°F | 65°F | 103°F 2020 | 57°F 2011 | 1% |
| Aug 22 | 95°F | 65°F | 104°F 1998 | 59°F 2002 | 1% |
| Aug 23 | 95°F | 65°F | 105°F 1998 | 58°F 2004 | 1% |
| Aug 24 | 95°F | 65°F | 106°F 2010 | 58°F 2004 | 1% |
| Aug 25 | 95°F | 65°F | 108°F 2010 | 60°F 2004 | 1% |
| Aug 26 | 95°F | 65°F | 106°F 2026 | 59°F 2006 | 1% |
| Aug 27 | 95°F | 65°F | 108°F 2009 | 60°F 2002 | 2% |
| Aug 28 | 95°F | 65°F | 110°F 2017 | 59°F 2002 | 2% |
| Aug 29 | 95°F | 65°F | 108°F 1998 | 58°F 2002 | 2% |
| Aug 30 | 95°F | 65°F | 109°F 1998 | 57°F 2010 | 2% |
| Aug 31 | 95°F | 65°F | 112°F 2017 | 56°F 1999 | 2% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (PDT).
- August 1
- sunrise 6:02 AM, sunset 7:51 PM
- August 31
- sunrise 6:23 AM, sunset 7:17 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USW00003102 (Ontario Intl AP), public domain. Records: NOAA GHCN-Daily, station USW00003102, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.