U.S. Frost Dates by Weather Station

NOAA station USC00205690 · Michigan

Frost Dates for Munising, MI

NOAA weather station Munising (USC00205690), Michigan · elevation 680 ft (207 m) · hardiness zone 5b*

  • Lower-risk planting dateafter June 2only 1 spring in 10 still has a frost later
  • Typical last frostMay 1650% chance of a frost after it
  • Typical first fall frostOctober 1450% chance of a frost before it
  • Frost-free season148 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Munising, MISpring: a frost after May 1 in 9 years out of 10, after May 16 in half of the years, after June 2 in 1 year out of 10. Fall: the first frost comes before September 30 in 1 year out of 10, before October 14 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 148 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 16First frost ~Oct 14Frost season at Munising, MISpring: a frost after May 1 in 9 years out of 10, after May 16 in half of the years, after June 2 in 1 year out of 10. Fall: the first frost comes before September 30 in 1 year out of 10, before October 14 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 148 days.JFMAMJJASONDLast frost ~May 16First frost ~Oct 14
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 2September 30
50% (typical)May 16October 14
90% (likely)May 1October 30
Frost-free season (32°F, 50% chance)
148 days
Hard frost (28°F), last in spring, 50% chance after
May 3
Hard frost (28°F), first in fall, 50% chance before
October 28

The last 15 years (2006–2020 normals)

Typical last frost May 15 (1 day earlier than the 30-year normal), typical first fall frost October 17 (3 days later). Frost-free season 154 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 Munising: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 2, 20% May 27, 30% May 23, 40% May 19, 50% May 16, 60% May 13, 70% May 9, 80% May 6, 90% May 1. Observed last spring frost in recent years: 2021 May 29, 2022 May 7, 2023 May 25, 2024 May 2, 2025 May 9.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 2May 16May 12021: May 292022: May 72023: May 252024: May 22025: May 9Fall at Munising: chance of a frost before this dateFall, chance of a frost before the date: 10% September 30, 20% October 5, 30% October 8, 40% October 11, 50% October 14, 60% October 17, 70% October 21, 80% October 24, 90% October 30. Observed first fall frost in recent years: 2021 November 1, 2022 October 8, 2023 October 22, 2024 November 2.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 30Oct 14Oct 302021: November 12022: October 82023: October 222024: 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 29November 1
2022May 7October 8
2023May 25October 22
2024May 2November 2
2025May 9incomplete record
2026incomplete recordseason not over yet

What these dates mean

September 30 is the cautious fall date for finishing the harvest of tender crops in Munising, as there is only a 10 % chance that a light frost has arrived earlier.

The cautious spring date for setting out tender crops is June 2, when a light frost later than that date is only a 10 % possibility; planting on May 1 carries a 90 % gamble. The 50% spring date is May 16 and the 50% fall date is October 14; these are median points where a light frost is equally likely before or after. The 50% hard-frost dates are May 3 in spring and October 28 in fall. A hard frost at 28 °F can injure plants that survive a light frost at 32 °F, making it a more serious threat. Across the 26-year record the two 32 °F 50% dates are 148 days apart.

How to read the probabilities

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

  • Spring: "10% after June 2" 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 30" 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 Munising, MINumbered nearest stations: 1 — Chatham Experiment Farm 2, MI — 13 mi; 2 — Marquette (USW00014838), MI — 35 mi; 3 — Manistique, MI — 37 mi; 4 — Marquette (USW00094850), MI — 43 mi; 5 — St. James 4 SSW Beaver, MI — 73 mi.MI25 mi · 40 km1. Chatham Experiment Farm 2, MI — 13 mi12. Marquette (USW00014838), MI — 35 mi23. Manistique, MI — 37 mi34. Marquette (USW00094850), MI — 43 mi45. St. James 4 SSW Beaver, MI — 73 mi5
  1. Chatham Experiment Farm 2, MI 13 mi (22 km)
  2. Marquette (USW00014838), MI 35 mi (57 km)
  3. Manistique, MI 37 mi (60 km)
  4. Marquette (USW00094850), MI 43 mi (69 km)
  5. St. James 4 SSW Beaver, MI 73 mi (118 km)

Sources

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

Station coordinates: 46.4122, -86.6625.