Sanibel, FL 33924 Frost Dates
33924, near Sanibel, FL: the frost window
Typically, the last spring freeze lands around 01/16, roughly 141 days out. Fall's first freeze usually shows up around 01/13, roughly 365 days after the last spring frost.
Zone 11a (40 to 45°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Sanibel, not a forecast for this year.
Stretching the season past the first frost
Sanibel's growing season runs out in roughly 20 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 01/16 isn't a guarantee
01/16 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 01/01 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 02/02 and only about 1 year in 10 sees frost after that.
Sanibel against the rest of the dataset
About 365 days separate Sanibel's last and first frost, putting it 1,850 of 40,283 ZIP codes nationally. Within FL, it ranks 798 of 1,609.
Learn more
Two guides worth reading on 33924: zone vs. frost date, on why Zone 11a and Sanibel's frost date answer different questions, and the frost range, on how to read the range around Sanibel's dates instead of trusting one.