San Marcos, TX 78666 Frost Dates
San Marcos, TX: when does the frost end?
Typically, the last spring freeze lands around 02/28, roughly 184 days out. Fall's first freeze usually shows up around 11/29, roughly 273 days after the last spring frost.
Zone 9a (20 to 25°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 San Marcos, not a forecast for this year.
Stretching the season past the first frost
With roughly 13 weeks until San Marcos's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 02/28 isn't a guarantee
02/28 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/01 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 03/21 and only about 1 year in 10 sees frost after that.
San Marcos against the rest of the dataset
About 273 days separate San Marcos's last and first frost, putting it 5,181 of 40,283 ZIP codes nationally. Within TX, it ranks 859 of 2,558.
Learn more
Before leaning on 78666's figures: zone vs. frost date explains why Zone 9a and San Marcos's frost date answer different questions, while the frost range explains how to read the range around San Marcos's dates instead of trusting one.