USDA Hardiness Zone 10a
Frost Dates for 78374 — Portland, Texas
NOAA 1991–2020 normals from Corpus Christi NWS, TX (44 ft), 13 miles southwest.
Updated
A freeze (32°F) reaches Portland in 88% of winters. When it does, the first fall frost comes around December 22 and the last spring frost around January 31; after March 2 the chance of another is under 9%.
- Last spring frost
- January 31
- First fall frost
- December 22
- Winters with a freeze
- 88%
- Hardiness zone
- 10a
50%, in freezing years
50%, in freezing years
32°F or below, 1991–2020
30 to 35°F (-1.1 to 1.7°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 13%
- Snow per year
- 0.3"
median, 1991–2020
median, 1991–2020
2 of 16 observed
NOAA normal
Frost risk by date in Portland
In the 88% of winters that bring a 32°F night, half of springs at Corpus Christi NWS, TX see their last 32°F night by January 31; only one in ten is past it by December 24, and one in ten still has one after March 2. Counting the winters with no freeze at all, the risk of a 32°F night after March 2 is under 9% and after January 31 44%. The 30 days between the even-odds date and the one-in-ten date is wider than at 91% 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 22 in half of years, as early as November 29 one year in ten, and holds off past February 1 one year in ten. A hard freeze of 28°F follows 10 days later, around January 1; in spring the one-in-ten date for 28°F is February 17, 13 days before the 32°F one. The freeze-free season lasts 331 days in a typical year, longer than at 95% of the 339 Texas stations; it reaches 365 days one year in ten and falls short of 291 one year in ten. On average 4 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 18 days longer, to about February 18, and return around December 7. A 24°F night is unusual: 15% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F99% of yrs | Jan 18 | Jan 29 | Feb 6 | Feb 12 | Feb 18 | Feb 24 | Mar 1 | Mar 4 | Mar 12 |
| 32°F88% of yrs | Dec 24 | Jan 5 | Jan 15 | Jan 24 | Jan 31 | Feb 5 | Feb 12 | Feb 21 | Mar 2 |
| 28°F52% of yrs | Dec 13 | Dec 23 | Dec 31 | Jan 5 | Jan 11 | Jan 21 | Jan 30 | Feb 5 | Feb 17 |
| 24°F15% of yrs | too rare for a date | ||||||||
| 20°F1% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F99% of yrs | Nov 16 | Nov 24 | Nov 29 | Dec 2 | Dec 7 | Dec 11 | Dec 17 | Dec 24 | Jan 4 |
| 32°F88% of yrs | Nov 29 | Dec 5 | Dec 10 | Dec 16 | Dec 22 | Dec 28 | Jan 4 | Jan 13 | Feb 1 |
| 28°F52% of yrs | Dec 7 | Dec 14 | Dec 21 | Dec 27 | Jan 1 | Jan 5 | Jan 11 | Jan 23 | Feb 4 |
| 24°F15% of yrs | too rare for a date | ||||||||
| 20°F1% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Corpus Christi NWS, 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 78374 →Compare Portland with another place →
Weather by month in Portland
August is the warmest month at Corpus Christi NWS, TX, averaging 93°F by day and 77°F at night; January is the coldest at 66°F and 47°F. From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 34% of years and March still brings one in 10% of years.
Warmth for growing adds up to 8,154 growing degree days a year (base 50°F), more than at 91% of the 351 Texas stations. 44% of them (3,564) have built up by the end of June, and August adds the most, 1,076. Precipitation totals 31.2 inches a year, most in September (5.4") and least in January (1.4"); May to September bring 56% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 66 | 47 | 1.4 | 55% | 1 | 238 |
| Feb | 70 | 51 | 1.4 | 34% | 1 | 315 |
| Mar | 75 | 58 | 2.3 | 10% | <1 | 502 |
| Apr | 81 | 63 | 2.0 | 0% | 0 | 659 |
| May | 86 | 71 | 3.3 | 0% | 0 | 873 |
| Jun | 90 | 75 | 3.5 | 0% | 0 | 978 |
| Jul | 92 | 76 | 2.5 | 0% | 0 | 1060 |
| Aug | 93 | 77 | 2.8 | 0% | 0 | 1076 |
| Sep | 89 | 73 | 5.4 | 0% | 0 | 926 |
| Oct | 84 | 66 | 2.7 | 0% | 0 | 766 |
| Nov | 75 | 56 | 2.0 | 11% | <1 | 471 |
| Dec | 68 | 49 | 1.9 | 51% | 1 | 292 |
Monthly normals 1991–2020 at Corpus Christi NWS, TX (44 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, Corpus Christi, TX, 14 miles southwest of Portland, has a last frost 3 days earlier (January 28), a first frost 1 day earlier (December 21).
When it snows in Portland, Texas
Measurable snow is rare here: only 2 of 16 winters from 1991 to 2020 recorded 0.1 inch or more at Corpus Christi NWS, TX, 13.4 miles away, so there is no typical first-snow date to plan around.
Where these figures come from
ZIP 78374 is 13 miles from Corpus Christi NWS, TX, which stands at 44 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 78374 in zone 10a, the band where the coldest night of the year averaged 30 to 35°F (-1.1 to 1.7°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.