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 37922
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 37922 in zone 7b (the coldest night of a typical year: 5 to 10°F).
The nearest station, Knoxville, TN, is 7 miles from the ZIP's center: its last spring frost comes after April 1 in half of years and after April 17 in one year in ten. By the USDA's method its plant hardiness zone is 7b.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Knoxville, TNKnoxville Airport | 7 mi | 962 ft | April 1 | April 17 | November 2 | 7b |
| Knoxville Experiment Station, TN | 8 mi | 830 ft | April 11 | April 29 | October 28 | 7b |
| Lenoir City, TN | 10 mi | 785 ft | April 5 | April 21 | November 1 | 7b |
| Oak Ridge Atdd, TN | 13 mi | 905 ft | April 5 | April 19 | November 1 | 7b |
| Oak Ridge, TNOak Ridge Asos | 14 mi | 910 ft | March 31 | April 15 | November 4 | 8a |
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 Knoxville
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) | May 2 | April 22 | April 14 | March 27 | October 24 | October 12 |
| 32°F | April 17 | April 7 | April 1 | March 14 | November 2 | October 21 |
| 28°F (hard freeze) | April 5 | March 28 | March 19 | February 28 | November 13 | November 1 |
| 24°F | March 27 | March 15 | March 6 | February 12 | November 27 | November 11 |
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.