Ontario Weather in September
Average highs run from 77°F on September 1 to 68°F on September 30, and lows from 58°F to 48°F. Normal precipitation for the month is 3.39 in over about 11 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
- 73°F
- Average low
- 53°F
- Precipitation
- 3.39 in
- Record high
- 98°FSep 1, 1943
- Record low
- 26°FSep 24, 1963
- Chance of a freeze
- 4%
- Days of 90°F or more
- 0.9
- Daylight
- 13 h 11 min to 11 h 47 min
- Cloud cover
- 67%
- Humidity
- 71%
- Dew point
- 52°F
- Wind
- 4.9 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.
| Date | Normal high | Normal low | Record high | Record low | Chance wet | Chance of snow |
|---|---|---|---|---|---|---|
| Sep 1 | 77°F | 58°F | 98°F 1943 | 41°F 1971 | 36% | 0% |
| Sep 2 | 77°F | 58°F | 98°F 1943 | 39°F 1967 | 36% | 0% |
| Sep 3 | 77°F | 57°F | 93°F 1973 | 39°F 1976 | 36% | 0% |
| Sep 4 | 77°F | 57°F | 96°F 1953 | 37°F 1987 | 36% | 0% |
| Sep 5 | 77°F | 57°F | 94°F 1973 | 40°F 1963 | 36% | 0% |
| Sep 6 | 76°F | 57°F | 94°F 2007 | 37°F 2000 | 36% | 0% |
| Sep 7 | 76°F | 56°F | 98°F 2007 | 40°F 1984 | 36% | 0% |
| Sep 8 | 76°F | 56°F | 95°F 2007 | 40°F 1982 | 36% | 0% |
| Sep 9 | 76°F | 56°F | 95°F 1959 | 36°F 1957 | 36% | 0% |
| Sep 10 | 75°F | 55°F | 95°F 1931 | 34°F 1956 | 37% | 0% |
| Sep 11 | 75°F | 55°F | 96°F 1931 | 36°F 1967 | 37% | 0% |
| Sep 12 | 75°F | 55°F | 91°F 2013 | 34°F 2006 | 37% | 0% |
| Sep 13 | 74°F | 54°F | 95°F 1931 | 36°F 1943 | 37% | 0% |
| Sep 14 | 74°F | 54°F | 92°F 1931 | 31°F 1963 | 37% | 0% |
| Sep 15 | 74°F | 54°F | 95°F 1939 | 38°F 2020 | 37% | 0% |
| Sep 16 | 73°F | 53°F | 90°F 1941 | 33°F 1964 | 37% | 0% |
| Sep 17 | 73°F | 53°F | 91°F 1941 | 34°F 1959 | 38% | 0% |
| Sep 18 | 73°F | 53°F | 90°F 1955 | 33°F 1959 | 38% | 0% |
| Sep 19 | 72°F | 52°F | 91°F 1942 | 34°F 2020 | 38% | 0% |
| Sep 20 | 72°F | 52°F | 90°F 1925 | 31°F 1929 | 39% | 0% |
| Sep 21 | 72°F | 52°F | 90°F 1931 | 29°F 1929 | 39% | 0% |
| Sep 22 | 71°F | 51°F | 90°F 1931 | 33°F 1929 | 40% | 0% |
| Sep 23 | 71°F | 51°F | 89°F 1959 | 31°F 1947 | 40% | 0% |
| Sep 24 | 70°F | 51°F | 91°F 1970 | 26°F 1963 | 41% | 0% |
| Sep 25 | 70°F | 50°F | 93°F 2007 | 31°F 1925 | 41% | 0% |
| Sep 26 | 70°F | 50°F | 91°F 2007 | 31°F 1925 | 42% | 0% |
| Sep 27 | 69°F | 49°F | 85°F 2017 | 31°F 1957 | 43% | 0% |
| Sep 28 | 69°F | 49°F | 89°F 2017 | 28°F 1957 | 43% | 0% |
| Sep 29 | 68°F | 49°F | 91°F 1959 | 31°F 1957 | 44% | 0% |
| Sep 30 | 68°F | 48°F | 87°F 1954 | 28°F 1991 | 45% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (EDT).
- September 1
- sunrise 6:33 AM, sunset 7:44 PM
- September 30
- sunrise 7:05 AM, sunset 6:52 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00309049 (Webster 2 Ne), public domain. Records: NOAA GHCN-Daily, station USC00307842, 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.