U.S. Frost Dates by Weather Station

NOAA station USW00014822 · Michigan

Frost Dates near Detroit, MI

NOAA weather station Detroit City Airport (USW00014822), Michigan · elevation 626 ft (191 m) · hardiness zone 6b*

Detroit is the nearest town to the station (5.7 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter May 6only 1 spring in 10 still has a frost later
  • Typical last frostApril 2150% chance of a frost after it
  • Typical first fall frostOctober 3150% chance of a frost before it
  • Frost-free season190 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season near Detroit, MISpring: a frost after April 7 in 9 years out of 10, after April 21 in half of the years, after May 6 in 1 year out of 10. Fall: the first frost comes before October 17 in 1 year out of 10, before October 31 in half of the years, before November 11 in 9 years out of 10. Typical frost-free season: 190 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 21First frost ~Oct 31Frost season near Detroit, MISpring: a frost after April 7 in 9 years out of 10, after April 21 in half of the years, after May 6 in 1 year out of 10. Fall: the first frost comes before October 17 in 1 year out of 10, before October 31 in half of the years, before November 11 in 9 years out of 10. Typical frost-free season: 190 days.JFMAMJJASONDLast frost ~Apr 21First frost ~Oct 31
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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 6October 17
50% (typical)April 21October 31
90% (likely)April 7November 11
Frost-free season (32°F, 50% chance)
190 days
Hard frost (28°F), last in spring, 50% chance after
April 8
Hard frost (28°F), first in fall, 50% chance before
November 9

The last 15 years (2006–2020 normals)

Typical last frost April 21 (same as the 30-year normal), typical first fall frost October 29 (2 days earlier). Frost-free season 191 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 near Detroit: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 6, 20% May 1, 30% April 27, 40% April 23, 50% April 21, 60% April 18, 70% April 16, 80% April 12, 90% April 7. Observed last spring frost in recent years: 2021 April 22, 2022 April 29, 2023 April 26, 2024 April 25, 2025 April 9, 2026 April 20.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 6Apr 21Apr 72021: April 222022: April 292023: April 262024: April 252025: April 92026: April 20Fall near Detroit: chance of a frost before this dateFall, chance of a frost before the date: 10% October 17, 20% October 21, 30% October 24, 40% October 28, 50% October 31, 60% November 1, 70% November 3, 80% November 6, 90% November 11. Observed first fall frost in recent years: 2021 November 4, 2022 November 14, 2023 October 31, 2024 November 29.Fall: first frostChance of a frost before this date10%50%90%Nov 1Dec 1Oct 17Oct 31Nov 112021: November 42022: November 142023: October 312024: November 29
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
2021April 22November 4
2022April 29November 14
2023April 26October 31
2024April 25November 29
2025April 9incomplete record
2026April 20season not over yet

What these dates mean

Setting out tender crops on April 7 in the Detroit area carries a 90 % chance of a frost later than that date, making it a gamble for gardeners. The light-frost chance drops to 10 % only after May 6, which is the cautious date for starting tender varieties.

The 50 % light-frost date is April 21 in spring and October 31 in fall; at each of those dates there is an even chance of a frost occurring later (spring) or earlier (fall). A cautious plan therefore plants after May 6 and finishes harvesting before October 17. The 50 % hard-frost dates are April 8 and November 9, and a hard frost at 28 °F can damage plants that survive a light frost at 32 °F, so it is a more severe threat.

How to read the probabilities

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

  • Spring: "10% after May 6" 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 17" 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, MINumbered nearest stations: 1 — Dearborn, MI — 13 mi; 2 — Detroit (Metro Airport), MI — 20 mi; 3 — Ann Arbor, MI — 34 mi; 4 — Port Huron, MI — 49 mi; 5 — Adrian, MI — 62 mi.MI25 mi · 40 km1. Dearborn, MI — 13 mi12. Detroit (Metro Airport), MI — 20 mi23. Ann Arbor, MI — 34 mi34. Port Huron, MI — 49 mi45. Adrian, MI — 62 mi5
  1. Dearborn, MI 13 mi (21 km)
  2. Detroit (Metro Airport), MI 20 mi (33 km)
  3. Ann Arbor, MI 34 mi (55 km)
  4. Port Huron, MI 49 mi (79 km)
  5. Adrian, MI 62 mi (99 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: 42.4092, -83.01.