Frost Date Calculator

From NOAA or your extension service, for your station and probability level.
From the seed packet: 6-8 weeks for tomatoes, 4 for squash, 10-12 for onions.
A margin for hardening off and for a late frost. 0 plants on the frost date itself.
From the seed packet.
Extra days a late crop needs as the days shorten; about two weeks is the usual allowance.
Days between the frost dates
143 days
Frost Date and Planting Calendar Calculator
Frost-free days between them
142 days
Growing season
20.4 weeks
Start seed indoors on
2026-04-03
Safe to transplant from
2026-05-29
Direct sowing can begin
2026-05-15
Last date to sow the autumn crop
2026-07-23
Harvest the autumn crop by
2026-10-05
Days from transplanting to the first frost
129 days
The crop fits the season
yes
Last frost falls on
Friday
Summary
A 143-day season from 2026-05-15 to 2026-10-05: sow indoors 2026-04-03, transplant from 2026-05-29, and sow the autumn crop by 2026-07-23.
Worked out from NOAA National Centers for Environmental Information, Freeze/Frost Occurrence Data (Climate Normals) and 2 other sources.
Average frost dates are probabilities, not promises: a 50% date is exceeded in half of years. Check the current forecast before setting tender plants out.

How this is worked out

4 steps
  1. 2026-05-15 to 2026-10-05 is 143 days, of which 142 lie strictly between the two frost dates.
  2. Sowing indoors 6 weeks (42 days) before the last frost gives 2026-04-03.
  3. Transplanting 2 weeks after the last frost gives 2026-05-29, leaving 129 days before the first autumn frost.
  4. An autumn crop needing 60 days plus a 14-day fall factor must be sown 74 days before 2026-10-05: 2026-07-23.

Results are general information, not financial, tax, legal, medical or engineering advice.