Frost dates by ZIP code: The nearest NOAA stations to your ZIP, 1991-2020 normals
Enter a five-digit ZIP code. PlainClimate finds its center (Census Bureau 2024) and the five nearest NOAA stations with frost dates, and shows each station's last spring and first autumn 32°F dates with its distance and elevation.
Frost dates near ZIP 77521
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 77521 in zone 9b (the coldest night of a typical year: 25 to 30°F).
The nearest station, Baytown, TX, is 7 miles from the ZIP's center: its last spring frost comes after February 20 in half of years and after March 14 in one year in ten. By the USDA's method its plant hardiness zone is 9b.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Baytown, TX | 7 mi | 26 ft | February 20 | March 14 | December 4 | 9b |
| Houston-Port, TX | 20 mi | 19 ft | February 2 | March 5 | December 25 | – |
| Anahuac, TX | 20 mi | 24 ft | February 12 | March 10 | December 6 | 9a |
| Liberty, TX | 20 mi | 35 ft | February 21 | March 17 | December 1 | – |
| Houston Hobby Airport, TX | 23 mi | 44 ft | January 30 | March 1 | December 28 | 9b |
Frost comes later in spring at higher and colder stations and earlier in low, open ground: prefer a station at a similar elevation to yours. Hardiness zone in the table: the USDA's rule (the average of each year's coldest night, 1991-2020) applied to the station's own record.
Every frost threshold at Baytown
NOAA publishes the dates for several temperatures and odds. A 30% spring date means a 3-in-10 chance of a later frost (the convention almanacs use); 50% is the median; 10% the cautious date.
| Threshold | Spring, 10% | Spring, 30% | Spring, 50% | Spring, 90% | Autumn, 50% | Autumn, 10% |
|---|---|---|---|---|---|---|
| 36°F (light frost) | March 28 | March 14 | March 6 | February 13 | November 20 | November 2 |
| 32°F | March 14 | March 2 | February 20 | January 23 | December 4 | November 12 |
| 28°F (hard freeze) | March 1 | February 10 | January 30 | December 25 | December 28 | November 25 |
| 24°F | February 11 | January 29 | January 16 | December 18 | January 4 | December 9 |
Source: NOAA NCEI 1991-2020 annual normals; ZIP centers: Census Bureau 2024 Gazetteer; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. Autumn 10%: one year in ten has its first frost before this date.