Key Biscayne Weather in September
Average highs run from 91°F on September 1 to 89°F on September 30, and lows from 79°F to 78°F. Normal precipitation for the month is 7.54 in over about 15 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
- 90°F
- Average low
- 79°F
- Precipitation
- 7.54 in
- Record high
- 97°FSep 8, 1987
- Record low
- 68°FSep 29, 1983
- Chance of a freeze
- 0%
- Days of 90°F or more
- 10.7
- Daylight
- 12 h 39 min to 11 h 55 min
- Cloud cover
- 62%
- Humidity
- 77%
- Dew point
- 76°F
- Wind
- 9.8 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 | 91°F | 79°F | 96°F 2021 | 71°F 1983 | 52% |
| Sep 2 | 91°F | 79°F | 94°F 2025 | 71°F 1949 | 52% |
| Sep 3 | 91°F | 79°F | 96°F 2007 | 71°F 1965 | 52% |
| Sep 4 | 91°F | 79°F | 95°F 2010 | 72°F 1984 | 52% |
| Sep 5 | 91°F | 79°F | 94°F 2021 | 72°F 1956 | 52% |
| Sep 6 | 91°F | 79°F | 96°F 2019 | 72°F 1984 | 52% |
| Sep 7 | 91°F | 79°F | 96°F 2022 | 72°F 1965 | 52% |
| Sep 8 | 91°F | 79°F | 97°F 1987 | 72°F 1950 | 52% |
| Sep 9 | 91°F | 79°F | 95°F 1949 | 70°F 1950 | 52% |
| Sep 10 | 91°F | 79°F | 95°F 1954 | 70°F 1950 | 52% |
| Sep 11 | 91°F | 79°F | 94°F 2022 | 69°F 1980 | 52% |
| Sep 12 | 91°F | 79°F | 94°F 2023 | 71°F 1980 | 52% |
| Sep 13 | 91°F | 79°F | 96°F 2023 | 71°F 1970 | 52% |
| Sep 14 | 90°F | 79°F | 94°F 1987 | 70°F 1965 | 51% |
| Sep 15 | 90°F | 79°F | 94°F 2006 | 71°F 1965 | 51% |
| Sep 16 | 90°F | 79°F | 95°F 2019 | 71°F 1961 | 51% |
| Sep 17 | 90°F | 79°F | 95°F 1989 | 72°F 1948 | 51% |
| Sep 18 | 90°F | 79°F | 95°F 1989 | 69°F 1985 | 51% |
| Sep 19 | 90°F | 79°F | 94°F 1995 | 70°F 1956 | 51% |
| Sep 20 | 90°F | 79°F | 94°F 1987 | 70°F 1985 | 51% |
| Sep 21 | 90°F | 79°F | 94°F 2022 | 71°F 1962 | 50% |
| Sep 22 | 90°F | 78°F | 94°F 1990 | 70°F 1950 | 50% |
| Sep 23 | 90°F | 78°F | 95°F 2022 | 71°F 1953 | 50% |
| Sep 24 | 90°F | 78°F | 92°F 2011 | 71°F 1950 | 50% |
| Sep 25 | 90°F | 78°F | 92°F 1987 | 70°F 1966 | 50% |
| Sep 26 | 90°F | 78°F | 94°F 1952 | 69°F 1983 | 50% |
| Sep 27 | 90°F | 78°F | 92°F 1958 | 69°F 1956 | 49% |
| Sep 28 | 89°F | 78°F | 93°F 1952 | 70°F 1983 | 49% |
| Sep 29 | 89°F | 78°F | 93°F 1952 | 68°F 1983 | 49% |
| Sep 30 | 89°F | 78°F | 93°F 1952 | 68°F 1983 | 49% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (EDT).
- September 1
- sunrise 7:01 AM, sunset 7:40 PM
- September 30
- sunrise 7:13 AM, sunset 7:08 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00081306 (Cape Florida), public domain. Records: NOAA GHCN-Daily, station USW00012839, 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.