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 46818
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 46818 in zone 6a (the coldest night of a typical year: -10 to -5°F).
The nearest station, Columbia City, IN, is 12 miles from the ZIP's center: its last spring frost comes after April 27 in half of years and after May 14 in one year in ten. By the USDA's method its plant hardiness zone is 5b.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Columbia City, IN | 12 mi | 834 ft | April 27 | May 14 | October 17 | 5b |
| Fort Wayne, INFort Wayne International Airport | 12 mi | 791 ft | April 24 | May 10 | October 21 | 6a |
| Garrett (1 mi S), IN | 15 mi | 870 ft | May 2 | May 16 | October 10 | – |
| Garrett, IN | 15 mi | 880 ft | April 29 | May 11 | October 17 | – |
| Woodburn, IN3 mi N | 21 mi | 710 ft | April 27 | May 11 | October 19 | – |
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 Columbia City
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 23 | May 13 | May 7 | April 23 | October 5 | September 22 |
| 32°F | May 14 | May 3 | April 27 | April 14 | October 17 | October 1 |
| 28°F (hard freeze) | May 2 | April 22 | April 16 | April 3 | October 29 | October 14 |
| 24°F | April 20 | April 12 | April 6 | March 21 | November 8 | October 28 |
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.