USDA Hardiness Zone 9b
Frost Dates for 77373 — Spring, Texas
NOAA 1991–2020 normals from Houston Intercont Airport, TX (95 ft), 6 miles south.
Updated
In Spring, the last spring frost (32°F) is around February 13 in half of years and has passed by March 12 in nine years out of ten. The first fall frost comes around December 9, as early as November 17 one year in ten, leaving a typical freeze-free season of 300 days (NOAA, Houston Intercont Airport, TX).
- Last spring frost
- February 13
- First fall frost
- December 9
- Growing season
- 300 days
- Hardiness zone
- 9b
50% probability
50% probability
freeze-free, 50%
25 to 30°F (-3.9 to -1.1°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 13%
- Snow per year
- 0.1"
median, 1991–2020
median, 1991–2020
4 of 30 observed
NOAA normal
Frost risk by date in Spring
Half of springs at Houston Intercont Airport, TX see their last 32°F night by February 13; only one in ten is past it by January 12, 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 27 days between the even-odds date and the one-in-ten date is wider than at 86% 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 9 in half of years, as early as November 17 one year in ten, and holds off past January 11 one year in ten. A hard freeze of 28°F follows 24 days later, around January 2; in spring the one-in-ten date for 28°F is March 2, 10 days before the 32°F one. The freeze-free season lasts 300 days in a typical year, longer than at 87% of the 339 Texas stations; it reaches 339 days one year in ten and falls short of 264 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 17 days longer, to about March 2, and return around November 25. A 24°F night is unusual: 33% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Feb 5 | Feb 16 | Feb 23 | Feb 27 | Mar 2 | Mar 6 | Mar 11 | Mar 16 | Mar 25 |
| 32°F99% of yrs | Jan 12 | Jan 24 | Jan 31 | Feb 5 | Feb 13 | Feb 20 | Feb 28 | Mar 4 | Mar 12 |
| 28°F77% of yrs | Dec 26 | Jan 7 | Jan 14 | Jan 20 | Jan 27 | Feb 1 | Feb 6 | Feb 18 | Mar 2 |
| 24°F33% of yrs | too rare for a date | ||||||||
| 20°F7% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 6 | Nov 12 | Nov 17 | Nov 21 | Nov 25 | Nov 29 | Dec 2 | Dec 6 | Dec 14 |
| 32°F99% of yrs | Nov 17 | Nov 25 | Dec 1 | Dec 4 | Dec 9 | Dec 15 | Dec 23 | Jan 1 | Jan 11 |
| 28°F77% of yrs | Dec 2 | Dec 11 | Dec 21 | Dec 29 | Jan 2 | Jan 6 | Jan 12 | Jan 20 | Feb 2 |
| 24°F33% of yrs | too rare for a date | ||||||||
| 20°F7% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Houston Intercont Airport, 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 77373 →Compare Spring with another place →
Weather by month in Spring
August is the warmest month at Houston Intercont Airport, TX, averaging 95°F by day and 75°F at night; January is the coldest at 64°F and 44°F. From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 55% of years and March still brings one in 28% of years.
Warmth for growing adds up to 7,657 growing degree days a year (base 50°F), more than at 81% of the 351 Texas stations. 43% of them (3,296) have built up by the end of June, and August adds the most, 1,090. Precipitation totals 52.0 inches a year, most in June (6.0") and least in February (3.0"); May to September bring 47% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 64 | 44 | 3.8 | 82% | 4 | 181 |
| Feb | 68 | 48 | 3.0 | 55% | 2 | 244 |
| Mar | 74 | 54 | 3.5 | 28% | 1 | 435 |
| Apr | 80 | 60 | 4.0 | 0% | 0 | 599 |
| May | 87 | 68 | 5.0 | 0% | 0 | 848 |
| Jun | 92 | 74 | 6.0 | 0% | 0 | 990 |
| Jul | 95 | 76 | 3.8 | 0% | 0 | 1088 |
| Aug | 95 | 75 | 4.8 | 0% | 0 | 1090 |
| Sep | 90 | 71 | 4.7 | 0% | 0 | 915 |
| Oct | 83 | 61 | 5.5 | 0% | 0 | 678 |
| Nov | 73 | 52 | 3.9 | 29% | 1 | 375 |
| Dec | 65 | 46 | 4.0 | 68% | 3 | 217 |
Monthly normals 1991–2020 at Houston Intercont Airport, TX (95 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, Houston Hooks Mem Airport, TX, 10 miles west of Spring, has a last frost 6 days later (February 19), a first frost 6 days earlier (December 3), a season 10 days shorter.
When it snows in Spring, Texas
Measurable snow is rare here: only 4 of 30 winters from 1991 to 2020 recorded 0.1 inch or more at Houston Intercont Airport, TX, 5.6 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 77373
| When | What to do |
|---|---|
| December 5 – December 19 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| December 19 – January 2 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 16 – January 30 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| February 13 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 16 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 25 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 9 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 77373 is 6 miles from Houston Intercont Airport, TX, which stands at 95 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 26 other ZIP codes share the station; its figures are presented in full for 77346 (Humble). The 2023 USDA Plant Hardiness Zone Map lists ZIP 77373 in zone 9b, the band where the coldest night of the year averaged 25 to 30°F (-3.9 to -1.1°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.