Lemont Weather in September
Average highs run from 77°F on September 1 to 67°F on September 30, and lows from 59°F to 49°F. Normal precipitation for the month is 3.95 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
- 72°F
- Average low
- 54°F
- Precipitation
- 3.95 in
- Record high
- 98°FSep 2, 1953
- Record low
- 28°FSep 22, 1904
- Chance of a freeze
- 1%
- Daylight
- 13 h 05 min to 11 h 48 min
- Cloud cover
- 60%
- Humidity
- 72%
- Dew point
- 51°F
- Wind
- 3.8 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 | 59°F | 97°F 1932 | 40°F 1890 | 35% | 0% |
| Sep 2 | 77°F | 59°F | 98°F 1953 | 39°F 1893 | 35% | 0% |
| Sep 3 | 77°F | 58°F | 97°F 1953 | 32°F 1893 | 35% | 0% |
| Sep 4 | 76°F | 58°F | 92°F 1898 | 38°F 1893 | 35% | 0% |
| Sep 5 | 76°F | 58°F | 92°F 1954 | 41°F 1928 | 35% | 0% |
| Sep 6 | 76°F | 58°F | 91°F 1922 | 39°F 1883 | 35% | 0% |
| Sep 7 | 75°F | 57°F | 90°F 1998 | 35°F 1888 | 35% | 0% |
| Sep 8 | 75°F | 57°F | 93°F 1929 | 39°F 1962 | 35% | 0% |
| Sep 9 | 75°F | 57°F | 92°F 1941 | 38°F 1986 | 35% | 0% |
| Sep 10 | 74°F | 56°F | 93°F 1964 | 34°F 1883 | 35% | 0% |
| Sep 11 | 74°F | 56°F | 94°F 1964 | 32°F 1917 | 35% | 0% |
| Sep 12 | 74°F | 56°F | 96°F 1896 | 35°F 1917 | 35% | 0% |
| Sep 13 | 73°F | 55°F | 93°F 1952 | 35°F 1985 | 35% | 0% |
| Sep 14 | 73°F | 55°F | 92°F 1952 | 35°F 1985 | 35% | 0% |
| Sep 15 | 73°F | 54°F | 91°F 1930 | 34°F 1895 | 35% | 0% |
| Sep 16 | 72°F | 54°F | 92°F 1897 | 30°F 1895 | 35% | 0% |
| Sep 17 | 72°F | 54°F | 90°F 1991 | 34°F 1923 | 35% | 0% |
| Sep 18 | 72°F | 53°F | 87°F 1972 | 33°F 1937 | 35% | 0% |
| Sep 19 | 71°F | 53°F | 88°F 1965 | 32°F 1916 | 35% | 0% |
| Sep 20 | 71°F | 53°F | 90°F 1932 | 34°F 1959 | 35% | 0% |
| Sep 21 | 70°F | 52°F | 89°F 1895 | 32°F 1956 | 35% | 0% |
| Sep 22 | 70°F | 52°F | 91°F 1914 | 28°F 1904 | 35% | 0% |
| Sep 23 | 70°F | 51°F | 90°F 1908 | 30°F 1947 | 36% | 0% |
| Sep 24 | 69°F | 51°F | 88°F 1930 | 30°F 1974 | 36% | 0% |
| Sep 25 | 69°F | 51°F | 89°F 1970 | 32°F 1887 | 36% | 0% |
| Sep 26 | 68°F | 50°F | 90°F 1900 | 31°F 1922 | 36% | 0% |
| Sep 27 | 68°F | 50°F | 86°F 1900 | 29°F 1947 | 36% | 0% |
| Sep 28 | 68°F | 50°F | 87°F 2017 | 28°F 1947 | 36% | 0% |
| Sep 29 | 67°F | 49°F | 88°F 1953 | 30°F 1942 | 36% | 0% |
| Sep 30 | 67°F | 49°F | 90°F 1953 | 31°F 1893 | 36% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (EDT).
- September 1
- sunrise 6:38 AM, sunset 7:43 PM
- September 30
- sunrise 7:07 AM, sunset 6:55 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00368449 (State College), public domain. Records: NOAA GHCN-Daily, station USC00368449, 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.