U.S. Frost Dates by Weather Station

NOAA station USC00215638 · Minnesota

Frost Dates near Morris, MN

NOAA weather station Morris W Central Research & Outreach (USC00215638), Minnesota · elevation 1140 ft (348 m) · hardiness zone 4b*

Morris is the nearest town to the station (1.9 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 17only 1 spring in 10 still has a frost later
  • Typical last frostMay 450% chance of a frost after it
  • Typical first fall frostOctober 150% chance of a frost before it
  • Frost-free season150 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season near Morris, MNSpring: a frost after April 21 in 9 years out of 10, after May 4 in half of the years, after May 17 in 1 year out of 10. Fall: the first frost comes before September 19 in 1 year out of 10, before October 1 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 150 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 4First frost ~Oct 1Frost season near Morris, MNSpring: a frost after April 21 in 9 years out of 10, after May 4 in half of the years, after May 17 in 1 year out of 10. Fall: the first frost comes before September 19 in 1 year out of 10, before October 1 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 150 days.JFMAMJJASONDLast frost ~May 4First 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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 17September 19
50% (typical)May 4October 1
90% (likely)April 21October 17
Frost-free season (32°F, 50% chance)
150 days
Hard frost (28°F), last in spring, 50% chance after
April 24
Hard frost (28°F), first in fall, 50% chance before
October 11

The last 15 years (2006–2020 normals)

Typical last frost May 5 (1 day later than the 30-year normal), typical first fall frost October 5 (4 days later). Frost-free season 154 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 Morris: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 17, 20% May 12, 30% May 9, 40% May 6, 50% May 4, 60% May 1, 70% April 30, 80% April 26, 90% April 21. Observed last spring frost in recent years: 2021 May 11, 2022 April 28, 2024 April 24, 2025 April 29, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%May 1May 17May 4Apr 212021: May 112022: April 282024: April 242025: April 292026: May 7Fall near Morris: chance of a frost before this dateFall, chance of a frost before the date: 10% September 19, 20% September 23, 30% September 26, 40% September 29, 50% October 1, 60% October 3, 70% October 5, 80% October 10, 90% October 17. Observed first fall frost in recent years: 2021 October 21, 2022 October 8, 2023 October 10, 2024 October 4, 2025 October 22.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 19Oct 1Oct 172021: October 212022: October 82023: October 102024: October 42025: October 22
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 21
2022April 28October 8
2023incomplete recordOctober 10
2024April 24October 4
2025April 29October 22
2026May 7season not over yet

What these dates mean

May 17 is the cautious spring date, giving a gardener a 10 % chance of a light frost later and permitting the setting out of tender crops. The 50% date is May 4, indicating an even chance of a light frost, while the 50% hard-frost date in spring is April 24, indicating an even chance of a hard frost. These median dates help gauge the level of risk when deciding when to expose sensitive plants.

September 19 is the cautious fall date, offering a 10 % chance that a light frost has arrived earlier and allowing the final harvest of tender crops. The 50% date is October 1, indicating an even chance of a light frost, and the 50% hard-frost date in fall is October 11, indicating an even chance of a hard frost. A hard frost at 28 °F can damage plants that would survive a 32 °F light frost.

How to read the probabilities

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

  • Spring: "10% after May 17" 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 19" 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 Morris, MNNumbered nearest stations: 1 — Artichoke Lake 1 E, MN — 19 mi; 2 — Glenwood, MN — 22 mi; 3 — Benson, MN — 23 mi; 4 — Alexandria, MN — 30 mi; 5 — Milan, MN — 32 mi.MNSDND25 mi · 40 km1. Artichoke Lake 1 E, MN — 19 mi12. Glenwood, MN — 22 mi23. Benson, MN — 23 mi34. Alexandria, MN — 30 mi45. Milan, MN — 32 mi5
  1. Artichoke Lake 1 E, MN 19 mi (30 km)
  2. Glenwood, MN 22 mi (35 km)
  3. Benson, MN 23 mi (36 km)
  4. Alexandria, MN 30 mi (48 km)
  5. Milan, MN 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: 45.59, -95.8744.