U.S. Frost Dates by Weather Station

NOAA station USW00094847 · Michigan

Frost Dates for Detroit (Metro Airport), MI

NOAA weather station Detroit Metro Airport (USW00094847), Michigan · elevation 631 ft (192 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 8only 1 spring in 10 still has a frost later
  • Typical last frostApril 2050% chance of a frost after it
  • Typical first fall frostOctober 2750% chance of a frost before it
  • Frost-free season188 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Detroit (Metro Airport), MISpring: a frost after April 6 in 9 years out of 10, after April 20 in half of the years, after May 8 in 1 year out of 10. Fall: the first frost comes before October 14 in 1 year out of 10, before October 27 in half of the years, before November 9 in 9 years out of 10. Typical frost-free season: 188 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 20First frost ~Oct 27Frost season at Detroit (Metro Airport), MISpring: a frost after April 6 in 9 years out of 10, after April 20 in half of the years, after May 8 in 1 year out of 10. Fall: the first frost comes before October 14 in 1 year out of 10, before October 27 in half of the years, before November 9 in 9 years out of 10. Typical frost-free season: 188 days.JFMAMJJASONDLast frost ~Apr 20First frost ~Oct 27
frost likely chance fading 90% → 10% frost-free in a typical yearThe year at a glance. Blue: frost is likely; the gradient fades as the chance drops from 90% to 10%; green: the frost-free part of a typical year.Today

Frost dates (32°F)

Probability of frost, based on 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 8October 14
50% (typical)April 20October 27
90% (likely)April 6November 9
Frost-free season (32°F, 50% chance)
188 days
Hard frost (28°F), last in spring, 50% chance after
April 8
Hard frost (28°F), first in fall, 50% chance before
November 7

The last 15 years (2006–2020 normals)

Typical last frost April 19 (1 day earlier than the 30-year normal), typical first fall frost October 28 (1 day later). Frost-free season 189 days.

A shorter, more recent NOAA period. The 30-year normals above remain the main reference: 15 years carry more year-to-year noise.

Add these dates to your calendar Yearly reminders for the typical last frost, the lower-risk planting date and the typical first fall frost (.ics).

How the chance of frost changes with the date

Spring at Detroit (Metro Airport): chance of a frost after this dateSpring, chance of a frost after the date: 10% May 8, 20% May 2, 30% April 28, 40% April 23, 50% April 20, 60% April 17, 70% April 15, 80% April 12, 90% April 6. Observed last spring frost in recent years: 2021 May 1, 2022 April 29, 2023 April 26, 2024 April 25, 2025 April 12, 2026 April 20.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 8Apr 20Apr 62021: May 12022: April 292023: April 262024: April 252025: April 122026: April 20Fall at Detroit (Metro Airport): chance of a frost before this dateFall, chance of a frost before the date: 10% October 14, 20% October 19, 30% October 22, 40% October 25, 50% October 27, 60% October 30, 70% November 1, 80% November 5, 90% November 9. Observed first fall frost in recent years: 2021 November 3, 2022 November 13, 2023 October 30, 2024 November 21, 2025 November 2.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 14Oct 27Nov 92021: November 32022: November 132023: October 302024: November 212025: November 2
Two charts, because spring and fall answer different questions: in spring, the chance that a frost still comes after a date; in fall, the chance that the first frost has already come before it. NOAA publishes these odds from 10% to 90%, so the lines stop there. ◆ marks the actual date in each recent year.

What actually happened in recent years

Observed dates of the last spring and first fall frost (32°F) at this station; ◆ marks them on the charts above
YearLast spring frostFirst fall frost
2021May 1November 3
2022April 29November 13
2023April 26October 30
2024April 25November 21
2025April 12November 2
2026April 20season not over yet

What these dates mean

The 188 days between the 50% dates in Detroit (Metro Airport) – April 20 and October 27 – mark the span in which a light frost is equally likely to have occurred or not.

For gardeners, the 50% dates are reference points: on April 20 a light frost has a 50% chance, and on October 27 the same odds apply for a frost earlier. A cautious spring plan uses the May 8 date, which carries only a 10% chance of a later light frost, while the April 6 date, with a 90% chance, represents a gamble. In the fall, the cautious deadline is October 14, offering a 10% chance that a frost has arrived earlier, whereas November 9, with a 90% chance, is the risky option.

Hard frosts at 28 °F, noted on April 8 and November 7, can damage plants more severely than the 32 °F light frosts.

How to read the probabilities

The dates are probabilities from 30 years of weather, not a forecast for this year.

  • Spring: "10% after May 8" means that in about one spring out of ten a frost still happens after that date. The 90% date is the earliest: a frost after it happens in most years.
  • Fall: "10% before October 14" means that in about one fall out of ten the first frost arrives before that date.
  • 50% is the typical date: half of the years are earlier, half are later.
  • A light frost (32°F) damages tender plants; a hard frost (28°F) also stops most hardy vegetables.

Nearby weather stations

Map of weather stations near Detroit (Metro Airport), MINumbered nearest stations: 1 — Dearborn, MI — 8 mi; 2 — Ann Arbor, MI — 18 mi; 3 — near Detroit, MI — 20 mi; 4 — Adrian, MI — 41 mi; 5 — near Toledo, OH — 51 mi.MIOHIN25 mi · 40 km1. Dearborn, MI — 8 mi12. Ann Arbor, MI — 18 mi23. near Detroit, MI — 20 mi34. Adrian, MI — 41 mi45. near Toledo, OH — 51 mi5
  1. Dearborn, MI 8 mi (12 km)
  2. Ann Arbor, MI 18 mi (28 km)
  3. near Detroit, MI 20 mi (33 km)
  4. Adrian, MI 41 mi (67 km)
  5. near Toledo, OH 51 mi (81 km)

Sources

* Hardiness zone 6b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 42.2314, -83.3308.