Frost dates in North Dakota

Across North Dakota's 125 NOAA stations with a frost every year, the typical last spring frost ranges from May 2 at Hillsboro 3 N (910 feet above sea level) to May 24 at Hettinger Municipal Airport (2,710 feet above sea level). The middle station's date is May 13.

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Last frost across North Dakota

The frost-free season runs from 115 days at Hettinger Municipal Airport to 158 days at Hillsboro 3 N.

These are typical dates: in half of springs the last frost comes later. Each place's page, and each ZIP code lookup, also gives the late-year date, after which only 1 spring in 10 has a frost. That's the safer date for tender plants.

Frost dates for North Dakota's larger places

Typical (1-in-2) dates. Each place's page has the early and late years, a planting calendar and a printable planner. Zones are for the ZIP code nearest each place's center.

Hardiness zones in North Dakota

North Dakota's 406 ZIP codes in the USDA list fall in zones 3b to 4b: 3b (13 percent), 4a (78 percent) and 4b (9 percent). Compared with the 2012 map, 20 percent of them moved to a warmer half zone, 80 percent stayed the same and 1 moved to a colder one.

A hardiness zone is about the coldest night of winter, which decides which shrubs, trees and perennials survive. Frost dates are about spring and fall, which decide when to plant. You need both. Read more about what the zones mean and what changed in 2023.

Every NOAA station in North Dakota

All 125 stations in North Dakota with frost statistics in NOAA's 1991 to 2020 normals, from A to Z. Station names are usually a town, an airport, or a distance and direction from a town. Find one near you and at a similar elevation.

Typical (1-in-2) dates at 32°F. For the early and late years, and a planting calendar built from your own dates, look up your ZIP code.