Diablo Grande Weather in September
Average highs run from 97°F on September 1 to 91°F on September 30, and lows from 59°F to 54°F. Normal precipitation for the month is 0.04 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
- 95°F
- Average low
- 57°F
- Precipitation
- 0.04 in
- Record high
- 112°FSep 7, 2022
- Record low
- 37°FSep 29, 2021
- Chance of a freeze
- 0%
- Days of 90°F or more
- 21.3
- Daylight
- 12 h 58 min to 11 h 50 min
- Cloud cover
- 16%
- Humidity
- 46%
- Dew point
- 45°F
- Wind
- 7.6 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 | 59°F | 103°F 1950 | 45°F 1951 | 1% |
| Sep 2 | 97°F | 59°F | 108°F 1950 | 48°F 1970 | 1% |
| Sep 3 | 97°F | 59°F | 106°F 1950 | 45°F 1951 | 1% |
| Sep 4 | 97°F | 59°F | 105°F 1950 | 43°F 1954 | 1% |
| Sep 5 | 97°F | 59°F | 106°F 1988 | 46°F 1965 | 1% |
| Sep 6 | 97°F | 59°F | 107°F 2022 | 45°F 2015 | 1% |
| Sep 7 | 97°F | 59°F | 112°F 2022 | 41°F 1964 | 1% |
| Sep 8 | 97°F | 59°F | 106°F 2022 | 47°F 1951 | 1% |
| Sep 9 | 96°F | 59°F | 108°F 2022 | 45°F 1964 | 2% |
| Sep 10 | 96°F | 58°F | 104°F 1984 | 41°F 1985 | 2% |
| Sep 11 | 96°F | 58°F | 104°F 2015 | 42°F 1985 | 2% |
| Sep 12 | 96°F | 58°F | 100°F 1960 | 40°F 1985 | 2% |
| Sep 13 | 96°F | 58°F | 102°F 1971 | 41°F 1996 | 2% |
| Sep 14 | 96°F | 58°F | 104°F 1971 | 40°F 1964 | 2% |
| Sep 15 | 95°F | 58°F | 102°F 1971 | 46°F 1969 | 2% |
| Sep 16 | 95°F | 58°F | 103°F 1971 | 46°F 1960 | 2% |
| Sep 17 | 95°F | 57°F | 103°F 1971 | 38°F 1988 | 2% |
| Sep 18 | 95°F | 57°F | 98°F 1984 | 45°F 1965 | 2% |
| Sep 19 | 95°F | 57°F | 100°F 1984 | 43°F 2019 | 3% |
| Sep 20 | 94°F | 57°F | 100°F 2000 | 44°F 2019 | 3% |
| Sep 21 | 94°F | 57°F | 99°F 2000 | 42°F 1954 | 3% |
| Sep 22 | 94°F | 56°F | 99°F 2015 | 40°F 1986 | 3% |
| Sep 23 | 94°F | 56°F | 98°F 2009 | 44°F 2017 | 3% |
| Sep 24 | 93°F | 56°F | 98°F 1991 | 45°F 1955 | 3% |
| Sep 25 | 93°F | 56°F | 100°F 2024 | 41°F 1988 | 3% |
| Sep 26 | 93°F | 55°F | 98°F 1952 | 38°F 1988 | 4% |
| Sep 27 | 92°F | 55°F | 99°F 2009 | 39°F 1988 | 4% |
| Sep 28 | 92°F | 55°F | 98°F 1963 | 45°F 1955 | 4% |
| Sep 29 | 92°F | 55°F | 98°F 2010 | 37°F 2021 | 4% |
| Sep 30 | 91°F | 54°F | 101°F 1966 | 39°F 1995 | 4% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (PDT).
- September 1
- sunrise 6:36 AM, sunset 7:34 PM
- September 30
- sunrise 7:00 AM, sunset 6:50 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00046168 (Newman), public domain. Records: NOAA GHCN-Daily, station USC00048999, 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.