Houston, Texas Frost Dates, Growing Season & Hardiness Zone

When is the last frost in Houston?

Not every winter freezes here. NOAA puts the chance of at least one 32°F night in a year at 90.2% at Houston-Port. The dates on this page describe the years that do freeze (NOAA computes them as conditional probabilities).

When a freeze does come, the last 32°F night is typically by Feb 2, and 1 in 10 of those years has one after Mar 5. 36°F nights (frost possible on plants) happen in 99.8% of years and typically end around Feb 24. 28°F hard freezes happen in 54.6% of years.

In Houston, late frosts can come well after the typical date. The safer 1-in-10 date (Mar 5) is 31 days after the typical date (Feb 2). Tender plants set out early will need cover on cold nights.

In years with a freeze, the typical last 32°F night comes around Feb 2, and the typical last 36°F night (frost possible on plants in low spots) around Feb 24, 22 days later. On clear, calm nights, frost can form on leaves even when the thermometer reads above freezing.

Is it too early to plant in Houston?

Before Feb 2 the odds of another 32°F night are better than even; after Mar 5 they are about 1 in 10 or less.

Today's risk is computed in your browser from the same NOAA probability table, shown as the range between the two nearest NOAA probability levels.

When is the first frost in Houston?

In the years that freeze, half have their first 32°F night by Dec 25, and 1 in 10 of them has one as early as Nov 27. The first 36°F night (frost possible on plants) typically comes around Dec 2. A 28°F hard freeze comes in 54.6% of years.

For fall crops, count back from Dec 25, or from Nov 27 to be safe. Our planting calendar does the math for each crop.

How long is Houston's growing season?

A typical year in Houston has 327 days between the last spring and first fall 32°F nights. In about 1 year in 10, there are fewer than 285 days.

This much frost-free time means many crops can go in twice, in spring and again for a fall harvest.

The station averages 7,687 growing degree days (base 50°F) a year. That number measures how much heat crops have to grow on.

How does Houston's season compare?

At 327 days, the typical frost-free season in Houston is the longest among the 6 Texas cities with frost dates on this site.

Nationwide, across the 56 cities with frost dates on this site, the typical frost-free season here outlasts the one in 50 of them and falls short of the one in 5.

Growing degree days (base 50°F)

Annual normal: 7,687 GDD (NOAA flag R, 11 years). Running total by the end of each month (sum of NOAA daily GDD normals, so the year-end total can differ slightly from the annual normal):

What growing zone is Houston? (USDA 2023)

On the 2023 USDA map, Houston is zone 9a–9b (20 to 30°F average coldest winter night). On the 2012 map, most of the city was 9a. Of the 113 city ZIPs listed in both tables, 111 moved up half a zone.

Zones: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed 2026-10-08. Shown as published in the ZIP tables; this page does not show a zone map. Not the official USDA Plant Hardiness Zone Map (official map: planthardiness.ars.usda.gov).

Does the new zone change Houston's frost dates?

No. Hardiness zones are based only on the average coldest winter temperature. They say nothing about when spring and fall frosts happen. Houston's frost dates come from NOAA's 1991–2020 frost probabilities, which did not change with the 2023 zone map. Use your zone to pick perennials that will survive winter, and your frost dates to time planting.

Why do Houston frost dates differ between websites?

Some sources list Feb 18 for Houston. That's the 30%-risk date: about 3 in 10 years with a freeze still have a 32°F night after it. Our headline date is Feb 2, the 50% (median) date.

We call Mar 5 the 'safer' date. It's the 10%-risk date: in about 1 in 10 years with a freeze, a 32°F night still comes after it.

Feb 24 is the typical (50%) date for a 36°F night (frost possible on plants), not a 32°F freeze. Any site that draws the line at 36°F will show later dates.

The choice of weather station matters too. The 7 stations within 25 miles of the city center that pass our quality rules give typical (50%) last 32°F frost dates from Jan 30 to Feb 19; see the table below.

Which weather station is this based on?

Station

Houston-Port (NOAA USC00414326, COOP)

Distance

7.1 mi ESE of the city center

Elevation

19 ft; city center 52 ft (USGS), difference −33 ft

Record

NOAA completeness flag R, 14 of 30 years (1991–2020)

Confidence

Medium (rule)

Confidence: Medium. The station passes our quality rules, but it's farther away or at a different elevation than ideal (7.1 mi, −33 ft; NOAA flag R, 14 of 30 years).

Caveat: NOAA flags this station's frost statistics 'R' (representative). They rest on 14 of the 30 years in 1991–2020, with missing months filled in from surrounding stations. The nearest station with a full 'S' (standard) record is Houston Hobby Airport, 12.1 mi away; its typical last frost is Jan 30.

Houston planting dates at a glance

Balanced dates use the 30%-risk last-frost date as the anchor. The Houston planting calendar has typical and safe dates, fall planting and a month-by-month list for 26 vegetables.

When to plant tomatoes in Houston · Fall planting dates for Houston

Frost dates near Houston

All Texas cities

Frequently asked questions

What is the average last frost date in Houston?

In years with a freeze (90.2% of years at Houston-Port), the typical (median, 50%) last 32°F night is Feb 2, based on NOAA 1991–2020 normals. For a safer target, use Mar 5: only about 1 in 10 of those years has a freeze after it.

When is the first frost in Houston?

Counting only years that freeze (90.2% of years at Houston-Port), the first 32°F night typically comes by Dec 25, and about 1 in 10 of those years sees one as early as Nov 27.

What growing zone is Houston, Texas?

Houston is in USDA hardiness zone 9a–9b on the current 2023 map. On the older 2012 map, most of the city was 9a, so older references may list that zone.

Is it too early to plant in Houston?

If you plant frost-tender crops before Feb 2, a 32°F night after planting is more likely than not in years with a freeze. For planting days from Feb 2 to Mar 5, that risk falls from 50% to 10% of those years. In any given year, NOAA puts the chance of a 32°F night at Houston-Port at 90.2%. Peas, lettuce and other cool-season crops can go in weeks earlier (see the planting calendar).

What temperature is a killing frost?

It depends on the crop. Tender plants such as tomatoes are killed by a light frost, which CSU Extension describes as 28–32°F; below 28°F is a heavy frost. We show NOAA odds for 36°F (frost possible on plants), 32°F (freeze, our headline) and 28°F (hard freeze).

Is first frost the same as first freeze?

Not exactly. A freeze is about the air reaching 32°F. Frost is ice on surfaces, which can form on calm, clear nights while the air is still a few degrees above freezing. The first 36°F night (frost possible on plants) in Houston typically comes around Dec 2. Freezes don't come every year here: NOAA puts the yearly chance of a 32°F night at 90.2%, and in years that have one, the first typically arrives around Dec 25.

Download & sources

• Add Houston frost & planting dates to your calendar (.ics, 2027)
• Printable planting calendar (PDF)
• How these numbers are calculated

Data: NOAA NCEI U.S. Climate Normals 1991–2020 (annual/seasonal and daily normals, station USC00414326); USDA Plant Hardiness Zone ZIP tables 2023 and 2012 by the PRISM Group, Oregon State University; Census 2020 ZIP/place relationship file; USGS elevation. Long-term odds, not a forecast. Figures and sentences are generated from these data by fixed rules; see the methodology. Last updated 2026-10-08.