Frost dates for ZIP 78665 (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, Georgetown Lake, TX (10 miles away).
- Average last spring frostMar 650% chance of a 32°F freeze after this date
- Average first fall frostNov 2450% chance of a 32°F freeze by this date
- Growing season (frost-free)259 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 13 |
| 50% (the "average" last frost) | Mar 6 |
| 10% (safe-side: only 1 year in 10 freezes later) | Mar 30 |
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 5 |
| 50% (the "average" first frost) | Nov 24 |
| 90% (late: most years have frozen by now) | Dec 10 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Mar 22 | Nov 13 |
| 32°F (freeze) | Mar 6 | Nov 24 |
| 28°F (hard freeze) | Feb 23 | Dec 5 |
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
70°F 55°F or warmer
24-hour average · latest 75°F, as of Oct 17, 7:00 PM CDT
Measured at TexMesonet (TWDB) station Texas State University Round Rock, 1 mi away. Daily averages: Thu 83°, Fri 76°.
4-inch depth
72°F 55°F or warmer
24-hour average · latest 75°F, as of Oct 17, 7:00 PM CDT
Measured at TexMesonet (TWDB) station Texas State University Round Rock, 1 mi away. Daily averages: Thu 83°, Fri 78°.
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 | 73° | 49° | Sunny |
| Monday | 77° | 54° | Mostly Sunny |
| Tuesday | 82° | 56° | Sunny |
| Wednesday | 85° | 57° | Sunny |
| Thursday | 88° | 59° | Sunny |
| Friday | 88° | 61° | Mostly 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 78665
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: Georgetown Lake, TX (NOAA GHCN-Daily ID USC00413507), elevation 874 ft, 10.1 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Austin Great Hills, TX | 12 mi | Mar 11 | Nov 20 |
| Taylor 1NW, TX | 13 mi | Mar 8 | Nov 21 |
| Austin-camp Mabry, TX | 17 mi | Feb 20 | Dec 3 |
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 78665?
The average (50% chance) last spring freeze of 32°F for ZIP 78665 is March 6. For a safer planting date, use March 30, when only 1 year in 10 still sees a later freeze.
When is the first frost in 78665?
The average first fall freeze is November 24. In 1 year in 10 it comes by November 5.
What hardiness zone is 78665?
ZIP 78665 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 78664 78674 78681 78717 78729 All Williamson County ZIPs