Frost dates for ZIP 78664 (Round Rock, TX)
Average last spring and first fall frost dates with 10%, 50% and 90% odds, from NOAA's 1991–2020 climate normals for the nearest weather station, Austin Great Hills, TX (10 miles away).
- Average last spring frostMar 1150% chance of a 32°F freeze after this date
- Average first fall frostNov 2050% chance of a 32°F freeze by this date
- Growing season (frost-free)254 daysmedian, 32°F threshold
- USDA hardiness zone9a20 to 25°F avg. coldest night
Last spring frost odds
| Chance of a 32°F freeze after this date | Date |
|---|---|
| 90% (early: most years still freeze after this) | Feb 22 |
| 50% (the "average" last frost) | Mar 11 |
| 10% (safe-side: only 1 year in 10 freezes later) | Mar 29 |
Most gardeners plant frost-tender crops (tomatoes, peppers, basil) after the 50% date, and closer to the 10% date for less risk.
First fall frost odds
| Chance the first 32°F freeze has happened by this date | Date |
|---|---|
| 10% (early: 1 year in 10 freezes this soon) | Nov 3 |
| 50% (the "average" first frost) | Nov 20 |
| 90% (late: most years have frozen by now) | Dec 9 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Mar 25 | Nov 10 |
| 32°F (freeze) | Mar 11 | Nov 20 |
| 28°F (hard freeze) | Mar 1 | Dec 3 |
n/a means NOAA did not publish a date at that threshold for this station (usually because it rarely gets that cold).
This week in Round Rock
Soil temperature now
2-inch depth
69°F 55°F or warmer
24-hour average · latest 71°F, as of Oct 17, 7:00 PM CDT
Measured at TexMesonet (TWDB) station Jim Embree Williamson, 3 mi away. Daily averages: Thu 78°, Fri 74°.
4-inch depth
73°F 55°F or warmer
24-hour average · latest 73°F, as of Oct 17, 7:00 PM CDT
Measured at TexMesonet (TWDB) station Jim Embree Williamson, 3 mi away. Daily averages: Thu 80°, Fri 77°.
Fall: Texas A&M AgriLife times fall pre-emergent (for winter weeds such as annual bluegrass) to soil cooling to about 70°F for several days. The 50–55°F band is the spring trigger. Always read and follow the product label.
7-day forecast and frost risk
No frost in the 7-day forecast.
| Period | High | Low | Forecast |
|---|---|---|---|
| Tonight | 47° | Mostly Clear | |
| Sunday | 74° | 49° | Sunny |
| Monday | 78° | 55° | Mostly Sunny |
| Tuesday | 83° | 57° | Sunny |
| Wednesday | 86° | 58° | Sunny |
| Thursday | 88° | 59° | Sunny |
| Friday | 89° | 61° | Sunny |
National Weather Service forecast, issued Oct 17, 8:28 PM CDT. Frost can form above 32°F on clear, calm nights. Full NWS forecast.
Free frost alerts for 78664
An email when the National Weather Service forecasts a freeze for this ZIP, plus the spring soil-temperature heads-up. At most a few a month.
Alerts open soon. This form is a preview and doesn't send anything yet.
Where these numbers come from
Station: Austin Great Hills, TX (NOAA GHCN-Daily ID USC00410433), elevation 880 ft, 9.5 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Georgetown Lake, TX | 13 mi | Mar 6 | Nov 24 |
| Austin-camp Mabry, TX | 14 mi | Feb 20 | Dec 3 |
| Taylor 1NW, TX | 15 mi | Mar 8 | Nov 21 |
The average last-frost dates of these stations span 22 days, a rough guide to local variation. See data sources & methods.
Questions
When is the last frost in 78664?
The average (50% chance) last spring freeze of 32°F for ZIP 78664 is March 11. For a safer planting date, use March 29, when only 1 year in 10 still sees a later freeze.
When is the first frost in 78664?
The average first fall freeze is November 20. In 1 year in 10 it comes by November 3.
What hardiness zone is 78664?
ZIP 78664 is in USDA zone 9a (20 to 25°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
Other ZIP codes in Williamson County
76527 76530 76537 76573 76574 76578 78613 78615 78626 78628 78633 78634 78642 78665 78674 78681 78717 78729 All Williamson County ZIPs