U.S. Frost Dates by Weather Station

NOAA station USW00014847 · Michigan

Frost Dates near Sault Ste. Marie, MI

NOAA weather station Sault Ste Marie Sanderson Field (USW00014847), Michigan · elevation 722 ft (220 m) · hardiness zone 5a*

Sault Ste. Marie is the nearest town to the station (1.2 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 27only 1 spring in 10 still has a frost later
  • Typical last frostMay 950% chance of a frost after it
  • Typical first fall frostOctober 1150% chance of a frost before it
  • Frost-free season151 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season near Sault Ste. Marie, MISpring: a frost after April 27 in 9 years out of 10, after May 9 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 11 in half of the years, before October 26 in 9 years out of 10. Typical frost-free season: 151 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 9First frost ~Oct 11Frost season near Sault Ste. Marie, MISpring: a frost after April 27 in 9 years out of 10, after May 9 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 11 in half of the years, before October 26 in 9 years out of 10. Typical frost-free season: 151 days.JFMAMJJASONDLast frost ~May 9First frost ~Oct 11
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 27September 26
50% (typical)May 9October 11
90% (likely)April 27October 26
Frost-free season (32°F, 50% chance)
151 days
Hard frost (28°F), last in spring, 50% chance after
April 27
Hard frost (28°F), first in fall, 50% chance before
October 26

The last 15 years (2006–2020 normals)

Typical last frost May 7 (2 days earlier than the 30-year normal), typical first fall frost October 17 (6 days later). Frost-free season 161 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 Sault Ste. Marie: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 27, 20% May 21, 30% May 17, 40% May 13, 50% May 9, 60% May 6, 70% May 2, 80% April 30, 90% April 27. Observed last spring frost in recent years: 2021 May 9, 2022 May 18, 2023 May 25, 2024 April 26, 2025 May 9, 2026 May 21.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 27May 9Apr 272021: May 92022: May 182023: May 252024: April 262025: May 92026: May 21Fall near Sault Ste. Marie: chance of a frost before this dateFall, chance of a frost before the date: 10% September 26, 20% October 1, 30% October 5, 40% October 7, 50% October 11, 60% October 13, 70% October 16, 80% October 20, 90% October 26. Observed first fall frost in recent years: 2021 October 21, 2022 October 10, 2023 October 12, 2024 October 17, 2025 October 25.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 26Oct 11Oct 262021: October 212022: October 102023: October 122024: 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 9October 21
2022May 18October 10
2023May 25October 12
2024April 26October 17
2025May 9October 25
2026May 21season not over yet

What these dates mean

Setting out tender crops on April 27 in the Sault Ste. Marie area carries a 90% chance of a frost later than this date, making it a gamble for gardeners. The 50% date of May 9 marks the point where a frost is equally likely to occur later or not; it is not itself a frost date. Hard frost at 28 °F can damage plants more severely than a light frost at 32 °F.

A cautious approach in spring waits until May 27, when only a 10% chance of a later frost remains, before placing tender crops outdoors. In the fall the cautious date to finish harvesting tender crops is September 26, with only a 10% chance that a frost has already arrived. The 50% date of October 11 signals even odds for a frost occurring on either side of the date. The 50% hard-frost dates are April 27 in spring and October 26 in fall.

How to read the probabilities

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

  • Spring: "10% after May 27" 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 September 26" 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 Sault Ste. Marie, MINumbered nearest stations: 1 — Detour Village, MI — 40 mi; 2 — Cheboygan, MI — 57 mi; 3 — Cross Village, MI — 66 mi; 4 — Pellston, MI — 67 mi; 5 — Onaway, MI — 74 mi.MI25 mi · 40 km1. Detour Village, MI — 40 mi12. Cheboygan, MI — 57 mi23. Cross Village, MI — 66 mi34. Pellston, MI — 67 mi45. Onaway, MI — 74 mi5
  1. Detour Village, MI 40 mi (64 km)
  2. Cheboygan, MI 57 mi (92 km)
  3. Cross Village, MI 66 mi (106 km)
  4. Pellston, MI 67 mi (107 km)
  5. Onaway, MI 74 mi (119 km)

Sources

* Hardiness zone 5a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 46.4794, -84.3572.