USDA Hardiness Zone 8a
Frost Dates for 78631 — Harper, Texas
NOAA 1991–2020 normals from Harper 3ENE, TX (2,110 ft), 6 miles east.
Updated
In Harper, the last spring frost (32°F) is around March 15 in half of years and has passed by April 12 in nine years out of ten. The first fall frost comes around November 15, as early as October 27 one year in ten, leaving a typical freeze-free season of 243 days (NOAA, Harper 3ENE, TX).
- Last spring frost
- March 15
- First fall frost
- November 15
- Growing season
- 243 days
- Hardiness zone
- 8a
50% probability
50% probability
freeze-free, 50%
10 to 15°F (-12.2 to -9.4°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 12%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
3 of 25 observed
NOAA normal
Frost risk by date in Harper
Half of springs at Harper 3ENE, TX see their last 32°F night by March 15; only one in ten is past it by February 24, and one in ten still has one after April 12. Planting tender crops after March 28 leaves a 30% risk of a frost on them, after April 3 20%, and after April 12 10%. The 28 days between the even-odds date and the one-in-ten date is wider than at 89% of the 339 Texas stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.
In fall the first 32°F night comes by November 15 in half of years, as early as October 27 one year in ten, and holds off past December 6 one year in ten. A hard freeze of 28°F follows 14 days later, around November 29; in spring the one-in-ten date for 28°F is March 28, 15 days before the 32°F one. The freeze-free season lasts 243 days in a typical year, shorter than at 56% of the 339 Texas stations; it reaches 273 days one year in ten and falls short of 211 one year in ten. On average 41 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 17 days longer, to about April 1, and return around November 4. Nights of 24°F, cold enough to damage hardier plants, come in 96% of winters and 16°F in 29%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Mar 7 | Mar 16 | Mar 22 | Mar 28 | Apr 1 | Apr 5 | Apr 10 | Apr 16 | Apr 24 |
| 32°F | Feb 24 | Mar 1 | Mar 5 | Mar 11 | Mar 15 | Mar 21 | Mar 28 | Apr 3 | Apr 12 |
| 28°F | Feb 5 | Feb 15 | Feb 22 | Feb 26 | Mar 2 | Mar 6 | Mar 11 | Mar 17 | Mar 28 |
| 24°F96% of yrs | Jan 3 | Jan 20 | Jan 31 | Feb 9 | Feb 16 | Feb 23 | Feb 28 | Mar 5 | Mar 12 |
| 20°F71% of yrs | Dec 18 | Dec 31 | Jan 7 | Jan 16 | Jan 25 | Feb 2 | Feb 13 | Feb 22 | Mar 4 |
| 16°F29% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 20 | Oct 24 | Oct 29 | Nov 1 | Nov 4 | Nov 7 | Nov 11 | Nov 16 | Nov 24 |
| 32°F | Oct 27 | Nov 2 | Nov 6 | Nov 10 | Nov 15 | Nov 20 | Nov 24 | Nov 30 | Dec 6 |
| 28°F | Nov 4 | Nov 12 | Nov 18 | Nov 23 | Nov 29 | Dec 3 | Dec 7 | Dec 14 | Dec 25 |
| 24°F96% of yrs | Nov 14 | Nov 23 | Dec 1 | Dec 6 | Dec 13 | Dec 21 | Dec 30 | Jan 5 | Jan 18 |
| 20°F71% of yrs | Nov 27 | Dec 6 | Dec 18 | Dec 26 | Jan 1 | Jan 5 | Jan 12 | Jan 24 | Feb 12 |
| 16°F29% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Harper 3ENE, TX, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 78631 →Compare Harper with another place →
Compared with the next station
The nearest other station, Kerrville 3 NNE, TX, 21 miles southeast of Harper and 313 feet lower, has a last frost 12 days later (March 27), a first frost 8 days earlier (November 7), a season 17 days shorter.
When it snows in Harper, Texas
Measurable snow is rare here: only 3 of 25 winters from 1991 to 2020 recorded 0.1 inch or more at Harper 3ENE, TX, 5.8 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 78631
| When | What to do |
|---|---|
| January 4 – January 18 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| January 18 – February 1 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| February 15 – March 1 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| March 15 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 23 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 1 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 15 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 78631 is 6 miles from Harper 3ENE, TX, which stands at 2,110 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 78631 in zone 8a, the band where the coldest night of the year averaged 10 to 15°F (-12.2 to -9.4°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.