U.S. Frost Dates by Weather Station

NOAA station USC00200032 · Michigan

Frost Dates for Adrian, MI

NOAA weather station Adrian 2 NNE (USC00200032), Michigan · elevation 760 ft (232 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 17only 1 spring in 10 still has a frost later
  • Typical last frostMay 150% chance of a frost after it
  • Typical first fall frostOctober 1550% chance of a frost before it
  • Frost-free season164 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Adrian, MISpring: a frost after April 18 in 9 years out of 10, after May 1 in half of the years, after May 17 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 15 in half of the years, before October 29 in 9 years out of 10. Typical frost-free season: 164 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 1First frost ~Oct 15Frost season at Adrian, MISpring: a frost after April 18 in 9 years out of 10, after May 1 in half of the years, after May 17 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 15 in half of the years, before October 29 in 9 years out of 10. Typical frost-free season: 164 days.JFMAMJJASONDLast frost ~May 1First frost ~Oct 15
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.

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 17October 1
50% (typical)May 1October 15
90% (likely)April 18October 29
Frost-free season (32°F, 50% chance)
164 days
Hard frost (28°F), last in spring, 50% chance after
April 20
Hard frost (28°F), first in fall, 50% chance before
October 27

The last 15 years (2006–2020 normals)

Typical last frost May 1 (same as the 30-year normal), typical first fall frost October 19 (4 days later). Frost-free season 169 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 Adrian: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 17, 20% May 12, 30% May 8, 40% May 5, 50% May 1, 60% April 29, 70% April 26, 80% April 22, 90% April 18. Observed last spring frost in recent years: 2021 May 13, 2022 April 28, 2023 April 27, 2024 April 26, 2025 April 17, 2026 May 2.Spring: last frostChance of a frost after this date10%50%90%May 1May 17May 1Apr 182021: May 132022: April 282023: April 272024: April 262025: April 172026: May 2Fall at Adrian: chance of a frost before this dateFall, chance of a frost before the date: 10% October 1, 20% October 5, 30% October 9, 40% October 12, 50% October 15, 60% October 17, 70% October 20, 80% October 24, 90% October 29. Observed first fall frost in recent years: 2021 October 24, 2023 October 23, 2024 October 17, 2025 October 25.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 1Oct 15Oct 292021: October 242023: October 232024: October 172025: October 25
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 13October 24
2022April 28incomplete record
2023April 27October 23
2024April 26October 17
2025April 17October 25
2026May 2season not over yet

What these dates mean

October 1 is the cautious fall date for Adrian, Michigan, marking the point when there is only a 10 % chance that a light frost has arrived and tender crops should be harvested.

For a gardener, the 50 % dates indicate the day on which the likelihood of a light frost later (spring) or earlier (fall) is exactly even. The median light-frost dates are May 1 in spring and October 15 in fall; the median hard-frost dates are April 20 and October 27. The span between the two 32 °F 50 % dates is 164 days.

In spring the cautious date for setting out tender crops is May 17, when the chance of a later frost has fallen to 10 %; in fall the cautious date to finish harvesting tender crops is October 1, when the chance of an earlier frost is only 10 %. A hard frost at 28 °F matters more because it can injure plants that survive a light frost at 32 °F.

How to read the probabilities

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

  • Spring: "10% after May 17" 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 1" 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 Adrian, MINumbered nearest stations: 1 — near Toledo, OH — 25 mi; 2 — Wauseon, OH — 28 mi; 3 — Ann Arbor, MI — 32 mi; 4 — Hillsdale, MI — 32 mi; 5 — near Jackson, MI — 33 mi.OHIN25 mi · 40 km1. near Toledo, OH — 25 mi12. Wauseon, OH — 28 mi23. Ann Arbor, MI — 32 mi34. Hillsdale, MI — 32 mi45. near Jackson, MI — 33 mi5
  1. near Toledo, OH 25 mi (41 km)
  2. Wauseon, OH 28 mi (46 km)
  3. Ann Arbor, MI 32 mi (51 km)
  4. Hillsdale, MI 32 mi (52 km)
  5. near Jackson, MI 33 mi (54 km)

Sources

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

Station coordinates: 41.9164, -84.0158.