U.S. Frost Dates by Weather Station

NOAA station USC00201675 · Michigan

Frost Dates near Coldwater, MI

NOAA weather station Coldwater State School (USC00201675), Michigan · elevation 984 ft (300 m) · hardiness zone 6a*

Coldwater is the nearest town to the station (1.6 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 18only 1 spring in 10 still has a frost later
  • Typical last frostMay 250% chance of a frost after it
  • Typical first fall frostOctober 1350% chance of a frost before it
  • Frost-free season163 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season near Coldwater, MISpring: a frost after April 18 in 9 years out of 10, after May 2 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before September 30 in 1 year out of 10, before October 13 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 163 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 2First frost ~Oct 13Frost season near Coldwater, MISpring: a frost after April 18 in 9 years out of 10, after May 2 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before September 30 in 1 year out of 10, before October 13 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 163 days.JFMAMJJASONDLast frost ~May 2First frost ~Oct 13
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 18September 30
50% (typical)May 2October 13
90% (likely)April 18October 30
Frost-free season (32°F, 50% chance)
163 days
Hard frost (28°F), last in spring, 50% chance after
April 21
Hard frost (28°F), first in fall, 50% chance before
October 28

The last 15 years (2006–2020 normals)

Typical last frost May 3 (1 day later than the 30-year normal), typical first fall frost October 18 (5 days later). Frost-free season 167 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 Coldwater: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 18, 20% May 13, 30% May 9, 40% May 5, 50% May 2, 60% April 30, 70% April 27, 80% April 23, 90% April 18. Observed last spring frost in recent years: 2021 May 12, 2022 April 28, 2023 May 21, 2024 April 26, 2025 May 10, 2026 May 2.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 18May 2Apr 182021: May 122022: April 282023: May 212024: April 262025: May 102026: May 2Fall near Coldwater: chance of a frost before this dateFall, chance of a frost before the date: 10% September 30, 20% October 4, 30% October 6, 40% October 10, 50% October 13, 60% October 17, 70% October 19, 80% October 23, 90% October 30. Observed first fall frost in recent years: 2021 October 22, 2022 October 7, 2023 October 22, 2024 October 17, 2025 October 25.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 30Oct 13Oct 302021: October 222022: October 72023: October 222024: 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 12October 22
2022April 28October 7
2023May 21October 22
2024April 26October 17
2025May 10October 25
2026May 2season not over yet

What these dates mean

In the Coldwater area, the cautious fall date to finish harvesting tender crops is September 30, when there is only a 10 % chance a light frost has arrived. That date marks the point at which most tender crops can be safely pulled in before frost becomes likely.

For spring planting, the cautious date to set out tender crops is May 18, which carries a 10 % chance of a later light frost; planting on April 18 carries a 90 % chance and is a gamble. The 50 % dates – May 2 in spring and October 13 in fall – indicate a 50 % chance of a light frost later than May 2 and a 50 % chance of a light frost earlier than October 13. The hard-frost median dates are April 21 and October 28; a hard frost at 28 °F can damage or kill plants that survive a 32 °F light frost, making it the more critical threshold.

How to read the probabilities

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

  • Spring: "10% after May 18" 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 Coldwater, MINumbered nearest stations: 1 — Hillsdale, MI — 18 mi; 2 — Angola, IN — 21 mi; 3 — Three Rivers, MI — 33 mi; 4 — near Jackson, MI — 34 mi; 5 — Charlotte, MI — 42 mi.MIINOH25 mi · 40 km1. Hillsdale, MI — 18 mi12. Angola, IN — 21 mi23. Three Rivers, MI — 33 mi34. near Jackson, MI — 34 mi45. Charlotte, MI — 42 mi5
  1. Hillsdale, MI 18 mi (29 km)
  2. Angola, IN 21 mi (33 km)
  3. Three Rivers, MI 33 mi (54 km)
  4. near Jackson, MI 34 mi (55 km)
  5. Charlotte, MI 42 mi (67 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: 41.9622, -84.9925.