USDA Hardiness Zone 9a
Frost Dates for 78017 — Dilley, Texas
NOAA 1991–2020 normals from Dilley, TX (550 ft), 5 miles southeast.
Updated
In Dilley, the last spring frost (32°F) is around February 16 in half of years and has passed by March 12 in nine years out of ten. The first fall frost comes around December 6, as early as November 16 one year in ten, leaving a typical freeze-free season of 296 days (NOAA, Dilley, TX).
- Last spring frost
- February 16
- First fall frost
- December 6
- Growing season
- 296 days
- Hardiness zone
- 9a
50% probability
50% probability
freeze-free, 50%
20 to 25°F (-6.7 to -3.9°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 6%
- Snow per year
- 0.2"
median, 1991–2020
median, 1991–2020
1 of 17 observed
NOAA normal
Frost risk by date in Dilley
Half of springs at Dilley, TX see their last 32°F night by February 16; only one in ten is past it by January 14, and one in ten still has one after March 12. Planting tender crops after February 28 leaves a 30% risk of a frost on them, after March 4 20%, and after March 12 10%. The 24 days between the even-odds date and the one-in-ten date is wider than at 76% 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 December 6 in half of years, as early as November 16 one year in ten, and holds off past January 3 one year in ten. A hard freeze of 28°F follows 17 days later, around December 23; in spring the one-in-ten date for 28°F is March 1, 11 days before the 32°F one. The freeze-free season lasts 296 days in a typical year, longer than at 85% of the 339 Texas stations; it reaches 336 days one year in ten and falls short of 261 one year in ten. On average 10 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 2, and return around November 23. A 24°F night is unusual: 38% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Feb 6 | Feb 16 | Feb 22 | Feb 27 | Mar 2 | Mar 6 | Mar 11 | Mar 16 | Mar 22 |
| 32°F99% of yrs | Jan 14 | Jan 26 | Feb 1 | Feb 8 | Feb 16 | Feb 21 | Feb 28 | Mar 4 | Mar 12 |
| 28°F83% of yrs | Dec 19 | Dec 30 | Jan 7 | Jan 16 | Jan 26 | Feb 2 | Feb 10 | Feb 19 | Mar 1 |
| 24°F38% of yrs | too rare for a date | ||||||||
| 20°F9% of yrs | too rare for a date | ||||||||
| 16°F1% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 5 | Nov 11 | Nov 16 | Nov 20 | Nov 23 | Nov 28 | Dec 1 | Dec 5 | Dec 11 |
| 32°F99% of yrs | Nov 16 | Nov 23 | Nov 28 | Dec 3 | Dec 6 | Dec 11 | Dec 16 | Dec 24 | Jan 3 |
| 28°F83% of yrs | Dec 1 | Dec 6 | Dec 12 | Dec 17 | Dec 23 | Dec 29 | Jan 4 | Jan 17 | Feb 4 |
| 24°F38% of yrs | too rare for a date | ||||||||
| 20°F9% of yrs | too rare for a date | ||||||||
| 16°F1% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Dilley, 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 78017 →Compare Dilley with another place →
Weather by month in Dilley
August is the warmest month at Dilley, TX, averaging 98°F by day and 74°F at night; January is the coldest at 66°F and 42°F. From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 61% of years and March still brings one in 27% of years.
Warmth for growing adds up to 7,844 growing degree days a year (base 50°F), more than at 86% of the 351 Texas stations. 44% of them (3,447) have built up by the end of June, and August adds the most, 1,113. Precipitation totals 25.1 inches a year, most in May (4.0") and least in January (1.2"); May to September bring 57% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 66 | 42 | 1.2 | 82% | 3 | 174 |
| Feb | 70 | 46 | 1.2 | 61% | 1 | 250 |
| Mar | 77 | 53 | 2.0 | 27% | 1 | 467 |
| Apr | 84 | 59 | 1.5 | 0% | 0 | 653 |
| May | 90 | 67 | 4.0 | 0% | 0 | 890 |
| Jun | 96 | 72 | 2.5 | 0% | 0 | 1014 |
| Jul | 97 | 74 | 2.2 | 0% | 0 | 1097 |
| Aug | 98 | 74 | 2.0 | 0% | 0 | 1113 |
| Sep | 92 | 70 | 3.7 | 0% | 0 | 918 |
| Oct | 85 | 61 | 2.2 | 1% | <1 | 700 |
| Nov | 73 | 51 | 1.4 | 34% | 1 | 378 |
| Dec | 66 | 43 | 1.2 | 78% | 4 | 192 |
Monthly normals 1991–2020 at Dilley, TX (550 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Cotulla La Salle Co Airport, TX, 19 miles south of Dilley, has a last frost 5 days earlier (February 11), a first frost 3 days earlier (December 3), a season 4 days longer.
When it snows in Dilley, Texas
Measurable snow is rare here: only 1 of 17 winters from 1991 to 2020 recorded 0.1 inch or more at Dilley, TX, 4.5 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 78017
| When | What to do |
|---|---|
| December 8 – December 22 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| December 22 – January 5 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 19 – February 2 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| February 16 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 13 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 22 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 6 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 78017 is 5 miles from Dilley, TX, which stands at 550 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 78061 (Pearsall). The 2023 USDA Plant Hardiness Zone Map lists ZIP 78017 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.
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.