Frost Dates for 78681 — Round Rock, Texas

Half of springs at Austin Great Hills, TX see their last 32°F night by March 11; only one in ten is past it by February 22, and one in ten still has one after March 29. Planting tender crops after March 19 leaves a 30% risk of a frost on them, after March 23 20%, and after March 29 10%. The 18 days between the even-odds date and the one-in-ten date is narrower than at 75% of the 339 Texas stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 20 in half of years, as early as November 3 one year in ten, and holds off past December 9 one year in ten. A hard freeze of 28°F follows 13 days later, around December 3; in spring the one-in-ten date for 28°F is March 19, 10 days before the 32°F one. The freeze-free season lasts 254 days in a typical year, longer than at 58% of the 339 Texas stations; it reaches 278 days one year in ten and falls short of 230 one year in ten. On average 27 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 14 days longer, to about March 25, and return around November 10. Nights of 24°F, cold enough to damage hardier plants, come in 94% of winters and 16°F in 22%.

August is the warmest month at Austin Great Hills, TX, averaging 96°F by day and 72°F at night; January is the coldest at 60°F and 38°F. A freezing night is all but certain in every month from December to February (a 90% chance or more). From April to October the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 77% of years.

Warmth for growing adds up to 6,698 growing degree days a year (base 50°F), more than at 62% of the 351 Texas stations. 41% of them (2,778) have built up by the end of June, and August adds the most, 1,064. Precipitation totals 37.1 inches a year, most in October (4.6") and least in February (2.0"); May to September bring 46% of it.

The nearest other station, Georgetown Lake, TX, 11 miles north of Round Rock, has a last frost 5 days earlier (March 6), a first frost 4 days later (November 24), a season 5 days longer.

Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Round Rock 3 NE, TX, 5 miles away, so there is no typical first-snow date to plan around.

ZIP 78681 is 8 miles from Austin Great Hills, TX, which stands at 880 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 15 other ZIP codes share the station; its figures are presented in full for 78660 (Pflugerville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 78681 in zone 9a, the band where the coldest night of the year averaged 20 to 25°F (-6.7 to -3.9°C) over 1991–2020; a zone describes winter lows, not frost dates.