USDA Hardiness Zone 8b
Frost Dates for 75457 — Mount Vernon, Texas
NOAA 1991–2020 normals from Mt Vernon, TX (447 ft), 3 miles north.
Updated
In Mount Vernon, the last spring frost (32°F) is around March 15 in half of years and has passed by April 6 in nine years out of ten. The first fall frost comes around November 16, as early as October 31 one year in ten, leaving a typical freeze-free season of 245 days (NOAA, Mt Vernon, TX).
- Last spring frost
- March 15
- First fall frost
- November 16
- Growing season
- 245 days
- Hardiness zone
- 8b
50% probability
50% probability
freeze-free, 50%
15 to 20°F (-9.4 to -6.7°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 30%
- Snow per year
- 0.4"
median, 1991–2020
median, 1991–2020
6 of 20 observed
NOAA normal
Frost risk by date in Mount Vernon
Half of springs at Mt Vernon, TX see their last 32°F night by March 15; only one in ten is past it by February 23, and one in ten still has one after April 6. Planting tender crops after March 25 leaves a 30% risk of a frost on them, after March 31 20%, and after April 6 10%. The 22 days between the even-odds date and the one-in-ten date is wider than at 63% 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 16 in half of years, as early as October 31 one year in ten, and holds off past December 4 one year in ten. A hard freeze of 28°F follows 15 days later, around December 1; in spring the one-in-ten date for 28°F is March 25, 12 days before the 32°F one. The freeze-free season lasts 245 days in a typical year, shorter than at 53% of the 339 Texas stations; it reaches 272 days one year in ten and falls short of 217 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 16 days longer, to about March 31, and return around November 4. Nights of 24°F, cold enough to damage hardier plants, come in 98% of winters and 16°F in 44%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Mar 8 | Mar 16 | Mar 21 | Mar 26 | Mar 31 | Apr 3 | Apr 7 | Apr 12 | Apr 19 |
| 32°F | Feb 23 | Mar 1 | Mar 6 | Mar 11 | Mar 15 | Mar 20 | Mar 25 | Mar 31 | Apr 6 |
| 28°F | Feb 4 | Feb 15 | Feb 21 | Feb 27 | Mar 2 | Mar 6 | Mar 10 | Mar 15 | Mar 25 |
| 24°F98% of yrs | Jan 13 | Jan 25 | Feb 1 | Feb 7 | Feb 14 | Feb 22 | Feb 28 | Mar 5 | Mar 12 |
| 20°F80% of yrs | Dec 28 | Jan 6 | Jan 15 | Jan 23 | Jan 29 | Feb 2 | Feb 8 | Feb 16 | Mar 2 |
| 16°F44% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 21 | Oct 26 | Oct 30 | Nov 1 | Nov 4 | Nov 8 | Nov 11 | Nov 16 | Nov 22 |
| 32°F | Oct 31 | Nov 4 | Nov 7 | Nov 11 | Nov 16 | Nov 20 | Nov 25 | Nov 30 | Dec 4 |
| 28°F | Nov 8 | Nov 14 | Nov 19 | Nov 25 | Dec 1 | Dec 3 | Dec 6 | Dec 12 | Dec 21 |
| 24°F98% of yrs | Nov 23 | Nov 30 | Dec 4 | Dec 9 | Dec 15 | Dec 22 | Dec 28 | Jan 2 | Jan 14 |
| 20°F80% of yrs | Dec 6 | Dec 15 | Dec 22 | Dec 29 | Jan 2 | Jan 7 | Jan 13 | Jan 19 | Feb 1 |
| 16°F44% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Mt Vernon, 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 75457 →Compare Mount Vernon with another place →
Weather by month in Mount Vernon
July is the warmest month at Mt Vernon, TX, averaging 94°F by day and 73°F at night; January is the coldest at 56°F and 34°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 77% of years and April still brings one in 19% of years.
Warmth for growing adds up to 6,021 growing degree days a year (base 50°F), fewer than at 71% of the 351 Texas stations. 40% of them (2,388) have built up by the end of June, and July adds the most, 1,040. Precipitation totals 48.2 inches a year, most in May (5.1") and least in August (3.1"); May to September bring 40% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 56 | 34 | 3.4 | 100% | 14 | 62 |
| Feb | 60 | 38 | 3.7 | 98% | 9 | 100 |
| Mar | 68 | 45 | 4.5 | 77% | 3 | 244 |
| Apr | 76 | 52 | 4.1 | 19% | <1 | 415 |
| May | 82 | 61 | 5.1 | 0% | 0 | 676 |
| Jun | 90 | 69 | 4.2 | 0% | 0 | 891 |
| Jul | 94 | 73 | 3.2 | 0% | 0 | 1040 |
| Aug | 95 | 72 | 3.1 | 0% | 0 | 1031 |
| Sep | 88 | 65 | 3.6 | 0% | 0 | 793 |
| Oct | 77 | 54 | 4.7 | 11% | <1 | 487 |
| Nov | 66 | 44 | 3.9 | 77% | 5 | 203 |
| Dec | 58 | 36 | 4.7 | 100% | 11 | 79 |
Monthly normals 1991–2020 at Mt Vernon, TX (447 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, Mt Pleasant, TX, 12 miles east of Mount Vernon, has a last frost 9 days later (March 24), a first frost 9 days earlier (November 7), a season 15 days shorter.
When it snows in Mount Vernon, Texas
Measurable snow is rare here: only 6 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Winnsboro 5 NNE, TX, 8.8 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 75457
| 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 24 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 2 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 16 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 75457 is 3 miles from Mt Vernon, TX, which stands at 447 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 75457 in zone 8b, the band where the coldest night of the year averaged 15 to 20°F (-9.4 to -6.7°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.