U.S. Frost Dates by Weather Station

NOAA station USC00208184 · Michigan

Frost Dates for Three Rivers, MI

NOAA weather station Three Rivers (USC00208184), Michigan · elevation 810 ft (247 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 15only 1 spring in 10 still has a frost later
  • Typical last frostApril 3050% chance of a frost after it
  • Typical first fall frostOctober 1750% chance of a frost before it
  • Frost-free season170 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Three Rivers, MISpring: a frost after April 16 in 9 years out of 10, after April 30 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 17 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 170 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 30First frost ~Oct 17Frost season at Three Rivers, MISpring: a frost after April 16 in 9 years out of 10, after April 30 in half of the years, after May 15 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 17 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 170 days.JFMAMJJASONDLast frost ~Apr 30First frost ~Oct 17
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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 15October 1
50% (typical)April 30October 17
90% (likely)April 16November 1
Frost-free season (32°F, 50% chance)
170 days
Hard frost (28°F), last in spring, 50% chance after
April 19
Hard frost (28°F), first in fall, 50% chance before
October 31

The last 15 years (2006–2020 normals)

Typical last frost April 30 (same as the 30-year normal), typical first fall frost October 19 (2 days later). Frost-free season 172 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 Three Rivers: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 15, 20% May 9, 30% May 6, 40% May 3, 50% April 30, 60% April 27, 70% April 24, 80% April 20, 90% April 16. Observed last spring frost in recent years: 2021 May 11, 2022 April 28, 2023 April 28, 2024 April 26, 2025 April 17, 2026 May 3.Spring: last frostChance of a frost after this date10%50%90%May 1May 15Apr 30Apr 162021: May 112022: April 282023: April 282024: April 262025: April 172026: May 3Fall at Three Rivers: chance of a frost before this dateFall, chance of a frost before the date: 10% October 1, 20% October 7, 30% October 11, 40% October 14, 50% October 17, 60% October 20, 70% October 23, 80% October 27, 90% November 1. Observed first fall frost in recent years: 2021 October 27, 2022 October 20, 2023 October 23, 2024 October 17, 2025 October 25.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 1Oct 17Nov 12021: October 272022: October 202023: 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 11October 27
2022April 28October 20
2023April 28October 23
2024April 26October 17
2025April 17October 25
2026May 3season not over yet

What these dates mean

Three Rivers enjoys a 170-day span between the 32°F 50% dates of April 30 and October 17, a period that contains the full cycle of planting, growth, and harvest. For gardeners the 50% date marks the moment a light frost is as likely as not, but it is not itself a frost date; the 50% date is April 30 in spring and the 50% date is October 17 in fall. The cautious spring date for setting out tender crops is May 15, which carries a 10 % chance that a frost will occur later, while the cautious fall date to finish harvesting tender crops is October 1, which carries a 10 % chance that a frost has already arrived. The hard-frost 50% dates are April 19 and October 31, and a hard frost at 28°F can damage plants more severely than 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 15" 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 Three Rivers, MINumbered nearest stations: 1 — Dowagiac, MI — 26 mi; 2 — Goshen, IN — 29 mi; 3 — near Coldwater, MI — 33 mi; 4 — Angola, IN — 37 mi; 5 — near South Bend, IN — 38 mi.OH25 mi · 40 km1. Dowagiac, MI — 26 mi12. Goshen, IN — 29 mi23. near Coldwater, MI — 33 mi34. Angola, IN — 37 mi45. near South Bend, IN — 38 mi5
  1. Dowagiac, MI 26 mi (41 km)
  2. Goshen, IN 29 mi (46 km)
  3. near Coldwater, MI 33 mi (54 km)
  4. Angola, IN 37 mi (59 km)
  5. near South Bend, IN 38 mi (61 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: 41.93, -85.6386.