U.S. Frost Dates by Weather Station

NOAA station USC00213303 · Minnesota

Frost Dates near Grand Rapids, MN

NOAA weather station Grand RPDS Forest Lab (USC00213303), Minnesota · elevation 1310 ft (399 m) · hardiness zone 4a*

Grand Rapids 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 31only 1 spring in 10 still has a frost later
  • Typical last frostMay 1750% chance of a frost after it
  • Typical first fall frostSeptember 2450% chance of a frost before it
  • Frost-free season130 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season near Grand Rapids, MNSpring: a frost after May 3 in 9 years out of 10, after May 17 in half of the years, after May 31 in 1 year out of 10. Fall: the first frost comes before September 10 in 1 year out of 10, before September 24 in half of the years, before October 7 in 9 years out of 10. Typical frost-free season: 130 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 17First frost ~Sep 24Frost season near Grand Rapids, MNSpring: a frost after May 3 in 9 years out of 10, after May 17 in half of the years, after May 31 in 1 year out of 10. Fall: the first frost comes before September 10 in 1 year out of 10, before September 24 in half of the years, before October 7 in 9 years out of 10. Typical frost-free season: 130 days.JFMAMJJASONDLast frost ~May 17First frost ~Sep 24
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 31September 10
50% (typical)May 17September 24
90% (likely)May 3October 7
Frost-free season (32°F, 50% chance)
130 days
Hard frost (28°F), last in spring, 50% chance after
May 6
Hard frost (28°F), first in fall, 50% chance before
October 5

The last 15 years (2006–2020 normals)

Typical last frost May 14 (3 days earlier than the 30-year normal), typical first fall frost September 27 (3 days later). Frost-free season 134 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 Grand Rapids: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 31, 20% May 26, 30% May 23, 40% May 20, 50% May 17, 60% May 14, 70% May 11, 80% May 7, 90% May 3. Observed last spring frost in recent years: 2021 May 29, 2022 May 5, 2023 May 3, 2024 April 25, 2025 May 3, 2026 May 13.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 31May 17May 32021: May 292022: May 52023: May 32024: April 252025: May 32026: May 13Fall near Grand Rapids: chance of a frost before this dateFall, chance of a frost before the date: 10% September 10, 20% September 15, 30% September 18, 40% September 21, 50% September 24, 60% September 27, 70% September 29, 80% October 3, 90% October 7. Observed first fall frost in recent years: 2021 October 17, 2022 September 28, 2024 October 4, 2025 October 7.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 10Sep 24Oct 72021: October 172022: September 282024: October 42025: October 7
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 29October 17
2022May 5September 28
2023May 3incomplete record
2024April 25October 4
2025May 3October 7
2026May 13season not over yet

What these dates mean

Setting out tender crops on the early spring date of May 3 in the Grand Rapids area carries a 90 % chance that a light frost will still occur later that season, making it a high-risk gamble for growers.

The cautious plan for spring uses the May 31 date, which has only a 10 % chance of a later frost, while the cautious fall date is September 10, also with a 10 % chance of an earlier frost. The 50 % dates—May 17 in spring and September 24 in fall—mark the points where a light frost has an even chance of occurring on either side, giving gardeners a clear mid-season benchmark.

A hard frost, defined at 28 °F, can damage plants that would survive a 32 °F light frost, so it represents a greater threat.

How to read the probabilities

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

  • Spring: "10% after May 31" 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 10" 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 Rapids, MNNumbered nearest stations: 1 — near Hibbing, MN — 32 mi; 2 — Leech Lake, MN — 34 mi; 3 — Floodwood, MN — 35 mi; 4 — Wright, MN — 47 mi; 5 — Eveleth, MN — 48 mi.MN25 mi · 40 km1. near Hibbing, MN — 32 mi12. Leech Lake, MN — 34 mi23. Floodwood, MN — 35 mi34. Wright, MN — 47 mi45. Eveleth, MN — 48 mi5
  1. near Hibbing, MN 32 mi (52 km)
  2. Leech Lake, MN 34 mi (55 km)
  3. Floodwood, MN 35 mi (56 km)
  4. Wright, MN 47 mi (75 km)
  5. Eveleth, MN 48 mi (77 km)

Sources

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

Station coordinates: 47.2436, -93.4975.