Round Rock, TX 78664 Frost Dates
78664, near Round Rock, TX: the frost window
The last spring frost here typically falls around 03/11, about 195 days from today. Fall's first freeze usually shows up around 11/20, roughly 254 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 Round Rock, not a forecast for this year.
Stretching the season past the first frost
Round Rock's growing season runs out in roughly 12 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 03/11 isn't a guarantee
03/11 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/22 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 03/29 and only about 1 year in 10 sees frost after that.
Round Rock against the rest of the dataset
At roughly 254 frost-free days, Round Rock places 6,984 of 40,283 ZIP codes in this dataset. Within TX, it ranks 1,512 of 2,558.
Learn more
Two guides worth reading on 78664: local microclimates, on what one yard in Round Rock can differ from the 78664 normal, and zone vs. frost date, on why Zone 9a and Round Rock's frost date answer different questions.