Ontario Weather in September
Average highs run from 95°F on September 1 to 87°F on September 30, and lows from 65°F to 61°F. Normal precipitation for the month is 0.10 in over about 1 wet days.
September day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
September at a glance
- Average high
- 91°F
- Average low
- 64°F
- Precipitation
- 0.10 in
- Record high
- 118°FSep 5, 2020
- Record low
- 51°FSep 27, 2013
- Chance of a freeze
- 0%
- Days of 90°F or more
- 17.5
- Daylight
- 12 h 52 min to 11 h 51 min
- Cloud cover
- 16%
- Humidity
- 41%
- Dew point
- 45°F
- Wind
- 5.1 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 |
|---|---|---|---|---|---|
| Sep 1 | 95°F | 65°F | 114°F 2017 | 57°F 2011 | 2% |
| Sep 2 | 95°F | 65°F | 110°F 2007 | 56°F 1999 | 2% |
| Sep 3 | 94°F | 65°F | 110°F 2007 | 56°F 2000 | 2% |
| Sep 4 | 94°F | 65°F | 109°F 2022 | 57°F 1999 | 2% |
| Sep 5 | 94°F | 65°F | 118°F 2020 | 57°F 1999 | 2% |
| Sep 6 | 94°F | 65°F | 117°F 2020 | 58°F 1999 | 2% |
| Sep 7 | 94°F | 65°F | 106°F 2024 | 55°F 1999 | 2% |
| Sep 8 | 94°F | 65°F | 109°F 2024 | 55°F 2002 | 2% |
| Sep 9 | 93°F | 65°F | 109°F 2026 | 55°F 2000 | 2% |
| Sep 10 | 93°F | 65°F | 102°F 2026 | 55°F 2008 | 2% |
| Sep 11 | 93°F | 65°F | 101°F 2017 | 57°F 1999 | 2% |
| Sep 12 | 93°F | 65°F | 105°F 2000 | 55°F 2005 | 2% |
| Sep 13 | 92°F | 65°F | 105°F 2014 | 56°F 2005 | 2% |
| Sep 14 | 92°F | 64°F | 108°F 2014 | 53°F 2016 | 2% |
| Sep 15 | 92°F | 64°F | 107°F 2014 | 56°F 1999 | 2% |
| Sep 16 | 92°F | 64°F | 107°F 2000 | 56°F 1999 | 2% |
| Sep 17 | 91°F | 64°F | 102°F 2000 | 55°F 2005 | 2% |
| Sep 18 | 91°F | 64°F | 106°F 2016 | 55°F 2010 | 2% |
| Sep 19 | 91°F | 64°F | 100°F 2015 | 56°F 2005 | 3% |
| Sep 20 | 90°F | 63°F | 104°F 2015 | 53°F 1999 | 3% |
| Sep 21 | 90°F | 63°F | 105°F 2003 | 53°F 2007 | 3% |
| Sep 22 | 90°F | 63°F | 105°F 2009 | 54°F 2017 | 3% |
| Sep 23 | 89°F | 63°F | 107°F 2002 | 54°F 2010 | 3% |
| Sep 24 | 89°F | 63°F | 103°F 2001 | 53°F 1998 | 3% |
| Sep 25 | 89°F | 62°F | 105°F 2009 | 52°F 2005 | 3% |
| Sep 26 | 88°F | 62°F | 107°F 2010 | 54°F 2005 | 3% |
| Sep 27 | 88°F | 62°F | 112°F 2010 | 51°F 2013 | 3% |
| Sep 28 | 87°F | 62°F | 100°F 1999 | 52°F 1998 | 3% |
| Sep 29 | 87°F | 61°F | 104°F 2020 | 53°F 1998 | 3% |
| Sep 30 | 87°F | 61°F | 108°F 2020 | 52°F 2019 | 4% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (PDT).
- September 1
- sunrise 6:24 AM, sunset 7:16 PM
- September 30
- sunrise 6:45 AM, sunset 6:36 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.