Rialto Weather in September
Average highs run from 97°F on September 1 to 87°F on September 30, and lows from 63°F to 58°F. Normal precipitation for the month is 0.23 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
- 93°F
- Average low
- 61°F
- Precipitation
- 0.23 in
- Record high
- 115°FSep 13, 1971
- Record low
- 41°FSep 9, 1901
- Chance of a freeze
- 0%
- Days of 90°F or more
- 20.0
- Daylight
- 12 h 52 min to 11 h 52 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 | 97°F | 63°F | 110°F 2007 | 48°F 1907 | 1% |
| Sep 2 | 97°F | 63°F | 110°F 1982 | 49°F 1926 | 1% |
| Sep 3 | 97°F | 63°F | 112°F 1988 | 49°F 1921 | 1% |
| Sep 4 | 97°F | 63°F | 109°F 1984 | 46°F 1912 | 1% |
| Sep 5 | 97°F | 62°F | 110°F 1984 | 45°F 1912 | 1% |
| Sep 6 | 97°F | 62°F | 112°F 1955 | 46°F 1912 | 1% |
| Sep 7 | 97°F | 62°F | 109°F 1898 | 47°F 1901 | 2% |
| Sep 8 | 96°F | 62°F | 108°F 1979 | 43°F 1914 | 2% |
| Sep 9 | 96°F | 62°F | 112°F 1979 | 41°F 1901 | 2% |
| Sep 10 | 96°F | 62°F | 107°F 1898 | 42°F 1901 | 2% |
| Sep 11 | 96°F | 62°F | 110°F 1971 | 46°F 1900 | 2% |
| Sep 12 | 95°F | 62°F | 114°F 1971 | 47°F 1952 | 2% |
| Sep 13 | 95°F | 61°F | 115°F 1971 | 46°F 1921 | 2% |
| Sep 14 | 95°F | 61°F | 107°F 1929 | 45°F 1939 | 2% |
| Sep 15 | 94°F | 61°F | 105°F 1937 | 46°F 1907 | 2% |
| Sep 16 | 94°F | 61°F | 109°F 2000 | 46°F 1921 | 2% |
| Sep 17 | 93°F | 61°F | 108°F 1922 | 45°F 1908 | 2% |
| Sep 18 | 93°F | 61°F | 105°F 1899 | 44°F 1924 | 2% |
| Sep 19 | 93°F | 60°F | 106°F 1899 | 46°F 1925 | 2% |
| Sep 20 | 92°F | 60°F | 104°F 1899 | 47°F 1925 | 3% |
| Sep 21 | 92°F | 60°F | 109°F 2003 | 46°F 2007 | 3% |
| Sep 22 | 91°F | 60°F | 106°F 1949 | 46°F 1944 | 3% |
| Sep 23 | 91°F | 60°F | 107°F 2002 | 46°F 1941 | 3% |
| Sep 24 | 90°F | 60°F | 106°F 1991 | 43°F 1923 | 3% |
| Sep 25 | 90°F | 59°F | 107°F 1963 | 44°F 1934 | 3% |
| Sep 26 | 89°F | 59°F | 108°F 2009 | 43°F 1948 | 3% |
| Sep 27 | 89°F | 59°F | 109°F 2010 | 45°F 1923 | 3% |
| Sep 28 | 88°F | 59°F | 107°F 1963 | 44°F 1971 | 3% |
| Sep 29 | 88°F | 59°F | 105°F 1963 | 43°F 1909 | 3% |
| Sep 30 | 87°F | 58°F | 108°F 1980 | 44°F 1940 | 4% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (PDT).
- September 1
- sunrise 6:23 AM, sunset 7:15 PM
- September 30
- sunrise 6:43 AM, sunset 6:35 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00047473 (Riverside Citrus Exp), public domain. Records: NOAA GHCN-Daily, station USC00047306, 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.