U.S. Frost Dates by Weather Station

NOAA station USC00213290 · Minnesota

Frost Dates for Grand Meadow, MN

NOAA weather station Grand Meadow (USC00213290), Minnesota · elevation 1350 ft (412 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 18only 1 spring in 10 still has a frost later
  • Typical last frostMay 650% chance of a frost after it
  • Typical first fall frostOctober 150% chance of a frost before it
  • Frost-free season146 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Grand Meadow, MNSpring: a frost after April 23 in 9 years out of 10, after May 6 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before September 17 in 1 year out of 10, before October 1 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 146 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 6First frost ~Oct 1Frost season at Grand Meadow, MNSpring: a frost after April 23 in 9 years out of 10, after May 6 in half of the years, after May 18 in 1 year out of 10. Fall: the first frost comes before September 17 in 1 year out of 10, before October 1 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 146 days.JFMAMJJASONDLast frost ~May 6First frost ~Oct 1
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 18September 17
50% (typical)May 6October 1
90% (likely)April 23October 13
Frost-free season (32°F, 50% chance)
146 days
Hard frost (28°F), last in spring, 50% chance after
April 27
Hard frost (28°F), first in fall, 50% chance before
October 9

The last 15 years (2006–2020 normals)

Typical last frost May 4 (2 days earlier than the 30-year normal), typical first fall frost October 6 (5 days later). Frost-free season 151 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 Grand Meadow: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 18, 20% May 14, 30% May 11, 40% May 9, 50% May 6, 60% May 4, 70% May 1, 80% April 29, 90% April 23. Observed last spring frost in recent years: 2021 May 12, 2022 May 24, 2023 May 4, 2024 April 25, 2025 April 30, 2026 May 12.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 18May 6Apr 232021: May 122022: May 242023: May 42024: April 252025: April 302026: May 12Fall at Grand Meadow: chance of a frost before this dateFall, chance of a frost before the date: 10% September 17, 20% September 21, 30% September 25, 40% September 28, 50% October 1, 60% October 3, 70% October 6, 80% October 9, 90% October 13. Observed first fall frost in recent years: 2021 October 17, 2022 September 28, 2023 October 11, 2024 October 8, 2025 October 8.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 17Oct 1Oct 132021: October 172022: September 282023: October 112024: October 82025: October 8
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 17
2022May 24September 28
2023May 4October 11
2024April 25October 8
2025April 30October 8
2026May 12season not over yet

What these dates mean

The cautious fall date in Grand Meadow for finishing the harvest is September 17. This date carries a 10% chance that a light frost has already arrived, making it a prudent point to conclude tender-crop harvesting before frost becomes likely.

For spring planting, the cautious date is May 18, when there is only a 10% chance of a light frost occurring later. The 50% dates—May 6 for spring and October 1 for fall—mark the moments when a frost is as likely as not, while the hard-frost 50% dates are April 27 and October 9. A hard frost at 28°F can injure or kill plants that would survive a light frost at 32°F, so it represents a more severe threat. The 27-year record provides the basis for these probability estimates.

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 17" 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 Grand Meadow, MNNumbered nearest stations: 1 — Rochester, MN — 14 mi; 2 — Austin, MN — 21 mi; 3 — Preston, MN — 25 mi; 4 — Osage, IA — 32 mi; 5 — Cresco, IA — 32 mi.MNIAWI25 mi · 40 km1. Rochester, MN — 14 mi12. Austin, MN — 21 mi23. Preston, MN — 25 mi34. Osage, IA — 32 mi45. Cresco, IA — 32 mi5
  1. Rochester, MN 14 mi (23 km)
  2. Austin, MN 21 mi (33 km)
  3. Preston, MN 25 mi (40 km)
  4. Osage, IA 32 mi (51 km)
  5. Cresco, IA 32 mi (52 km)

Sources

* Hardiness zone 4b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 43.7047, -92.5644.