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 78550
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 78550 in zone 10a (the coldest night of a typical year: 30 to 35°F).
The nearest station, Harlingen, TX, is 2 miles from the ZIP's center: its last spring frost comes after January 8 in half of years and after February 17 in one year in ten. By the USDA's method its plant hardiness zone is 10a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Harlingen, TXHarlingen Rio Grande Airport | 2 mi | 34 ft | January 8 | February 17 | December 29 | 10a |
| Harlingen station, TX | 4 mi | 38 ft | January 9 | February 4 | January 3 | 10a |
| Santa Rosa, TX3 mi WNW | 13 mi | 50 ft | January 10 | February 24 | December 27 | 10a |
| Raymondville, TX | 16 mi | 31 ft | January 21 | February 27 | December 26 | – |
| Weslaco, TX | 20 mi | 75 ft | January 8 | February 18 | December 31 | – |
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 Harlingen
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 3 | February 16 | January 31 | December 28 | December 13 | November 18 |
| 32°F | February 17 | January 27 | January 8 | December 12 | December 29 | December 2 |
| 28°F (hard freeze) | February 1 | January 9 | January 2 | December 14 | January 1 | December 13 |
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.