Frost Dates for 78665 — Round Rock, Texas

Half of springs at Johnson City 2N, TX see their last 32°F night by March 22; only one in ten is past it by February 27, and one in ten still has one after April 11. Planting tender crops after March 31 leaves a 30% risk of a frost on them, after April 4 20%, and after April 11 10%. The 20 days between the even-odds date and the one-in-ten date is narrower than at 51% of the 339 Texas stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 9 in half of years, as early as October 25 one year in ten, and holds off past November 30 one year in ten. A hard freeze of 28°F follows 13 days later, around November 22; in spring the one-in-ten date for 28°F is March 28, 14 days before the 32°F one. The freeze-free season lasts 235 days in a typical year, shorter than at 69% of the 339 Texas stations; it reaches 261 days one year in ten and falls short of 207 one year in ten. On average 42 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 13 days longer, to about April 4, and return around November 1. Nights of 24°F, cold enough to damage hardier plants, come in 99% of winters and 16°F in 52%.

August is the warmest month at Johnson City 2N, TX, averaging 97°F by day and 71°F at night; January is the coldest at 62°F and 35°F. A freezing night is all but certain in every month from December to February (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 82% of years and April still brings one in 29% of years.

Warmth for growing adds up to 6,614 growing degree days a year (base 50°F), more than at 59% of the 351 Texas stations. 42% of them (2,750) have built up by the end of June, and August adds the most, 1,045. Precipitation totals 33.2 inches a year, most in May (4.0") and least in December (1.9"); May to September bring 45% of it.

The nearest other station, Blanco, TX, 9 miles south of Round Rock and 173 feet higher, has a last frost 2 days earlier (March 20), a first frost 1 day later (November 10), a season 1 day longer.

Measurable snow is rare here: only 6 of 23 winters from 1991 to 2020 recorded 0.1 inch or more at Johnson City 2N, TX, 6.3 miles away, so there is no typical first-snow date to plan around.

ZIP 78665 is 6 miles from Johnson City 2N, TX, which stands at 1,137 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 78665 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.