U.S. Frost Dates by Weather Station

NOAA station USC00213174 · Minnesota

Frost Dates for Glenwood, MN

NOAA weather station Glenwood 2 WNW (USC00213174), Minnesota · elevation 1198 ft (365 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 27only 1 spring in 10 still has a frost later
  • Typical last frostMay 1150% chance of a frost after it
  • Typical first fall frostSeptember 2750% chance of a frost before it
  • Frost-free season139 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Glenwood, MNSpring: a frost after April 28 in 9 years out of 10, after May 11 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 13 in 1 year out of 10, before September 27 in half of the years, before October 9 in 9 years out of 10. Typical frost-free season: 139 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 11First frost ~Sep 27Frost season at Glenwood, MNSpring: a frost after April 28 in 9 years out of 10, after May 11 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 13 in 1 year out of 10, before September 27 in half of the years, before October 9 in 9 years out of 10. Typical frost-free season: 139 days.JFMAMJJASONDLast frost ~May 11First frost ~Sep 27
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 27September 13
50% (typical)May 11September 27
90% (likely)April 28October 9
Frost-free season (32°F, 50% chance)
139 days
Hard frost (28°F), last in spring, 50% chance after
May 1
Hard frost (28°F), first in fall, 50% chance before
October 6

The last 15 years (2006–2020 normals)

Typical last frost May 9 (2 days earlier than the 30-year normal), typical first fall frost September 30 (3 days later). Frost-free season 140 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 Glenwood: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 27, 20% May 22, 30% May 18, 40% May 14, 50% May 11, 60% May 8, 70% May 4, 80% May 1, 90% April 28.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 27May 11Apr 28Fall at Glenwood: chance of a frost before this dateFall, chance of a frost before the date: 10% September 13, 20% September 19, 30% September 22, 40% September 25, 50% September 27, 60% September 30, 70% October 2, 80% October 5, 90% October 9.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 13Sep 27Oct 9
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.

What these dates mean

Planting tender crops on April 28 in Glenwood is a gamble, because a light frost later than that date occurs with a 90% chance. The cautious spring date for tender crops is May 27, when only a 10% chance of a later light frost remains.

The 50% date in spring is May 11, marking the point where odds of a light frost later are even, and the 50% date in fall is September 27, when odds of a light frost earlier are even. For a prudent fall schedule, the cautious date is September 13, which carries only a 10% chance that a light frost has arrived earlier.

Hard frost, defined at 28 °F, can harm plants that survive a 32 °F light frost, so the median hard-frost dates of May 1 and October 6 are important thresholds for gardeners.

How to read the probabilities

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

  • Spring: "10% after May 27" 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 13" 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 Glenwood, MNNumbered nearest stations: 1 — Alexandria, MN — 15 mi; 2 — near Morris, MN — 22 mi; 3 — Benson, MN — 25 mi; 4 — Long Prairie, MN — 34 mi; 5 — Artichoke Lake 1 E, MN — 38 mi.SDND25 mi · 40 km1. Alexandria, MN — 15 mi12. near Morris, MN — 22 mi23. Benson, MN — 25 mi34. Long Prairie, MN — 34 mi45. Artichoke Lake 1 E, MN — 38 mi5
  1. Alexandria, MN 15 mi (24 km)
  2. near Morris, MN 22 mi (35 km)
  3. Benson, MN 25 mi (40 km)
  4. Long Prairie, MN 34 mi (55 km)
  5. Artichoke Lake 1 E, MN 38 mi (61 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: 45.6583, -95.4392.