Nassau County Weather in September
Average highs run from 89°F on September 1 to 85°F on September 30, and lows from 73°F to 67°F. Normal precipitation for the month is 7.56 in over about 12 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
- 87°F
- Average low
- 71°F
- Precipitation
- 7.56 in
- Record high
- 100°FSep 4, 1944
- Record low
- 48°FSep 19, 1981
- Chance of a freeze
- 0%
- Days of 90°F or more
- 9.0
- Daylight
- 12 h 46 min to 11 h 53 min
- Cloud cover
- 59%
- Humidity
- 81%
- Dew point
- 71°F
- Wind
- 4.7 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 | 89°F | 73°F | 95°F 1944 | 62°F 1999 | 46% |
| Sep 2 | 89°F | 73°F | 98°F 1947 | 57°F 1999 | 46% |
| Sep 3 | 89°F | 72°F | 97°F 1970 | 64°F 1972 | 46% |
| Sep 4 | 89°F | 72°F | 100°F 1944 | 65°F 2025 | 45% |
| Sep 5 | 89°F | 72°F | 99°F 1941 | 63°F 1997 | 45% |
| Sep 6 | 89°F | 72°F | 97°F 1944 | 61°F 1997 | 45% |
| Sep 7 | 89°F | 72°F | 97°F 2019 | 62°F 2016 | 45% |
| Sep 8 | 88°F | 72°F | 98°F 1990 | 61°F 2011 | 44% |
| Sep 9 | 88°F | 72°F | 98°F 1939 | 61°F 2016 | 44% |
| Sep 10 | 88°F | 72°F | 97°F 1939 | 62°F 1956 | 44% |
| Sep 11 | 88°F | 72°F | 99°F 1939 | 62°F 1998 | 43% |
| Sep 12 | 88°F | 71°F | 96°F 1991 | 62°F 1953 | 43% |
| Sep 13 | 88°F | 71°F | 97°F 1991 | 61°F 2015 | 43% |
| Sep 14 | 88°F | 71°F | 96°F 1991 | 60°F 2015 | 42% |
| Sep 15 | 87°F | 71°F | 96°F 1938 | 59°F 1940 | 42% |
| Sep 16 | 87°F | 71°F | 97°F 1990 | 57°F 2001 | 41% |
| Sep 17 | 87°F | 71°F | 96°F 2019 | 60°F 2001 | 41% |
| Sep 18 | 87°F | 70°F | 95°F 1972 | 58°F 1981 | 41% |
| Sep 19 | 87°F | 70°F | 98°F 1942 | 48°F 1981 | 40% |
| Sep 20 | 87°F | 70°F | 96°F 1942 | 48°F 1981 | 40% |
| Sep 21 | 86°F | 70°F | 97°F 1990 | 56°F 1981 | 39% |
| Sep 22 | 86°F | 70°F | 96°F 1990 | 55°F 1938 | 39% |
| Sep 23 | 86°F | 69°F | 94°F 1951 | 55°F 1938 | 38% |
| Sep 24 | 86°F | 69°F | 94°F 2019 | 53°F 1990 | 38% |
| Sep 25 | 86°F | 69°F | 96°F 2019 | 51°F 1990 | 37% |
| Sep 26 | 86°F | 69°F | 97°F 2019 | 54°F 1940 | 37% |
| Sep 27 | 85°F | 68°F | 94°F 1970 | 54°F 1940 | 36% |
| Sep 28 | 85°F | 68°F | 94°F 1986 | 57°F 1962 | 36% |
| Sep 29 | 85°F | 68°F | 94°F 1944 | 53°F 1993 | 35% |
| Sep 30 | 85°F | 67°F | 94°F 1939 | 50°F 1967 | 35% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (EDT).
- September 1
- sunrise 7:04 AM, sunset 7:50 PM
- September 30
- sunrise 7:20 AM, sunset 7:13 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USW00013889 (Jacksonville), public domain. Records: NOAA GHCN-Daily, station USW00013889, 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.