For Houston, the closest thing to a frost calendar comes from NOAA’s 30-70% probability band for a 32°F freeze: last spring frost lands between February 4 and March 1, first fall frost between December 1 and December 19. That’s a real, sourced window, not a guess. What changes the answer is where you actually garden, because Texas covers roughly 268,000 square miles and four separate USDA hardiness zones.
The frost dates for Texas
The dates above come from NOAA NCEI’s 1991-2020 Climate Normals for station USW00012960, better known as Houston Intercontinental Airport (IAH). NOAA doesn’t publish a single “frost date” the way a wall calendar might. Instead it tracks the range of days when a 32°F freeze has a 30 to 70 percent chance of occurring. That’s why you see a window rather than a fixed date: February 4 is the early edge of that probability band, March 1 the late edge, for spring. December 1 and December 19 mark the same band in the fall.
Even within Houston, this figure moves. IAH sits well north of downtown, and NOAA’s own station network shows Hobby Airport, closer to the coast and to Galveston Bay, running about two weeks milder than IAH in both directions. That two-week gap inside one metro area is a useful warning before we even leave the city limits.
Now stretch that same logic across the rest of the state. The Texas Panhandle sits in a cold-air path that freezes far earlier in fall and lingers far later in spring than anything the Gulf Coast experiences. Hill Country and North Texas fall somewhere in between, shaped by elevation and distance from the coast’s moderating effect. None of those regions share the IAH station’s data, and no single Texas-wide frost date exists in the way a smaller state might publish one.
Why the range matters more than a single date
Treating February 4 as “the” last frost and planting tender seedlings that day is a common mistake. That date is the early edge of a probability band, meaning a freeze after February 4 is still common, just less likely than before it. Gardeners who plant at the earliest edge of the window are accepting real risk in exchange for a head start.
- Early edge of the band (Feb 4 spring / Dec 19 fall): higher risk, longer potential season
- Late edge of the band (Mar 1 spring / Dec 1 fall): lower risk, shorter potential season
Neither edge is “correct.” Each is a trade-off between season length and frost risk, and the right choice depends on what you’re growing and how much a lost planting would cost you.
How long the growing season actually is here
Do the arithmetic on the IAH window and Houston’s frost-free season runs long by almost any U.S. standard. Counting from the earliest possible spring frost (February 4) to the latest possible fall frost (December 19) gives a season stretching close to 319 days. Counting the more conservative combination, latest spring frost (March 1) to earliest fall frost (December 1), still leaves about 275 days. Either way, Houston gardeners are working with somewhere between roughly nine and eleven months of frost-free growing, depending on which edge of each probability band you plan around.
That’s the number for Houston specifically, tied to the IAH station. It is not a Texas-wide season length, and treating it as one would badly overstate what gardeners in the northern and western parts of the state actually get. The USDA Plant Hardiness Zone Map, built from 1991-2020 normals, places Texas across zones 6a through 10a. That range alone tells you the state contains both some of the mildest winters in the continental U.S. and stretches cold enough to sit two full zones colder.
What the hardiness zone does and doesn’t tell you
It’s worth being precise about what a USDA zone number actually measures, because gardeners often ask it to do too much work. The system is built on a single variable: the average annual extreme minimum winter temperature recorded at a given location. It says nothing directly about when your last spring frost falls, how long your frost-free season runs, or how much summer heat you’ll face. A zone number is a useful shorthand for which perennials and woody plants can survive winter where you live. It’s a poor substitute for a frost calendar when you’re deciding when to sow lettuce or transplant tomatoes.
Put those two pieces of data together and a clearer picture emerges. Houston’s position toward the mild end of that 6a-10a range, combined with the IAH freeze-probability window, explains why coastal Texas gardeners can often push both ends of the calendar in ways that would fail two hundred miles inland or north.
Turning these dates into a sowing date
Frost dates only become useful once you translate them into an actual planting day, and that translation depends on what you’re growing. Seed packets and extension guides typically describe a plant in terms of weeks before or after the last frost, so the IAH window becomes your starting point for Houston-area gardens specifically.
For a warm-season crop that seed packaging describes as wanting to go into the ground “after last frost,” the practical range runs from February 4 at the earliest to March 1 at the latest, again matching how much risk you’re willing to accept. Starting seeds indoors ahead of transplanting pushes the calculation back further still, since most guidance calls for starting six to eight weeks before the intended transplant date, meaning a Houston gardener aiming for an early-March transplant would count backward to early or mid-January for the seed tray.
Fall crops work the same way in reverse. A cool-season vegetable that needs a certain number of days to mature before frost gets counted backward from the first fall frost window of December 1 to December 19. Miss that backward count and a slow-maturing crop simply runs out of season before the freeze probability climbs.
Where to check before you commit
None of this replaces local guidance for your specific county, since soil, water access, and crop variety all interact with frost timing in ways a single article can’t cover. Texas A&M AgriLife Extension (agrilifeextension.tamu.edu) maintains county-level offices across the state and is the land-grant university extension service for Texas, a reasonable next stop for anything specific to your region rather than to the Houston station referenced here.
The core habit worth building is simple: identify which edge of the NOAA probability band matches your risk tolerance, count backward or forward from it based on the crop’s stated timing, and treat the result as a planning target rather than a guarantee.
Why your own garden differs from this figure
A NOAA station measures air temperature at one fixed point, under standardized conditions, at an airport. Your backyard is not an airport, and that gap explains most of the difference between the published window and what you actually observe on a cold morning.
Cold air is dense and flows downhill, pooling in low spots, ditches, and the bottom of slopes. A garden bed at the low point of a yard can see frost on nights when a bed thirty feet away, slightly higher up, stays clear. Urban and suburban areas also generate their own heat, from pavement, buildings, and vehicle traffic, an effect strong enough that city centers routinely run several degrees warmer overnight than surrounding open land. That’s part of why Hobby Airport, closer to Houston’s urban core and the coast, trends about two weeks milder than IAH despite both stations sitting within the same metro area.
Structures and plantings on your own property add another layer. A south-facing wall holds heat and can shield nearby plants by several degrees. A stand of trees or a fence breaks the wind that would otherwise strip warmth from the soil surface on a clear, cold night. Open, exposed beds with no windbreak lose heat faster and frost first.
None of this means the NOAA window is wrong. It means the window describes conditions at one specific airport station, and your own frost timing will sit somewhere in relation to it, sometimes earlier, sometimes later, depending on elevation, exposure, and how much concrete surrounds you.
Common questions
What is the last frost date in Houston, Texas?
Based on NOAA NCEI’s 1991-2020 Climate Normals for station IAH, the last spring frost typically falls between February 4 and March 1, reflecting the range where a 32°F freeze has a 30 to 70 percent probability of occurring.
Does Texas have one frost date for the whole state?
No single date applies statewide. Texas spans four USDA hardiness zones, from 6a to 10a, and the Gulf Coast figures cited here for Houston do not represent conditions in the Panhandle, Hill Country, or North Texas.
Why does the same city show different frost dates at different stations?
Local factors such as distance from the coast, urban heat, and elevation shift the numbers even within one metro area. Hobby Airport, closer to Houston’s core and to the coast, runs roughly two weeks milder than the IAH station used for the figures in this article.
Where can Texas gardeners get frost guidance specific to their county?
Texas A&M AgriLife Extension (agrilifeextension.tamu.edu) operates county-level offices across the state and is the land-grant extension service for Texas, a better starting point for region-specific advice than a single Houston-area station.