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Frost odds · NOAA 1991-2020 · Cleveland Hopkins

When the freezing nights stop, and start again.

Thirty years of nightly lows at Cleveland Hopkins International Airport (NOAA station USW00014820), about 13 miles west of Garfield Heights, summarized by NOAA as odds. Seed Clock uses the 32°F rows; the 28°F rows (a hard freeze) are here for reference.

Spring: the last 32°F night

The chance that a freezing night still comes after the date.

Chance of a later freeze32°F28°F
10%May 5Apr 21
20%Apr 30Apr 16
30%Apr 27Apr 12
40%Apr 23Apr 8
50%Apr 20Apr 5
60%Apr 17Apr 3
70%Apr 14Apr 1
80%Apr 9Mar 29
90%Apr 4Mar 22

Fall: the first 32°F night

The chance that the first freezing night has already come before the date.

Chance of an earlier freeze32°F28°F
10%Oct 21Nov 1
20%Oct 26Nov 5
30%Oct 30Nov 7
40%Nov 1Nov 10
50%Nov 3Nov 13
60%Nov 5Nov 16
70%Nov 8Nov 20
80%Nov 12Nov 24
90%Nov 17Nov 29

Freeze-free season (32°F)

198 days in a middle year

At least 175 days in 9 years of 10; at least 217 days in 1 year of 10.

The three choices on Seed Clock

  • Bold (1 in 2) spring Apr 20, fall Nov 3. Plant on the middle date: in half of springs a freezing night still comes later.
  • Usual (3 in 10) spring Apr 27, fall Oct 30. The in-between choice and our default: a later freezing night in about 3 springs out of 10.
  • Careful (1 in 10) spring May 5, fall Oct 21. Wait for the safe side: a later freezing night in about 1 spring out of 10.

Frost odds · chance of a freezing night after your spring date

Your own garden can differ: frost settles in low spots and valleys first, and pavement and walls keep city lots warmer. Source: NOAA NCEI U.S. Climate Normals 1991-2020, annual/seasonal normals for USW00014820 (fields ANN-TMIN-PRBLST, PRBFST and PRBGSL), downloaded October 10, 2026.