U.S. Frost Dates by Weather Station

NOAA station USC00214534 · Minnesota

Frost Dates for Lake Wilson, MN

NOAA weather station Lake Wilson (USC00214534), Minnesota · elevation 1653 ft (504 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 19only 1 spring in 10 still has a frost later
  • Typical last frostMay 750% chance of a frost after it
  • Typical first fall frostSeptember 2950% chance of a frost before it
  • Frost-free season145 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Lake Wilson, MNSpring: a frost after April 25 in 9 years out of 10, after May 7 in half of the years, after May 19 in 1 year out of 10. Fall: the first frost comes before September 15 in 1 year out of 10, before September 29 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 145 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 7First frost ~Sep 29Frost season at Lake Wilson, MNSpring: a frost after April 25 in 9 years out of 10, after May 7 in half of the years, after May 19 in 1 year out of 10. Fall: the first frost comes before September 15 in 1 year out of 10, before September 29 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 145 days.JFMAMJJASONDLast frost ~May 7First frost ~Sep 29
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.Today

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 19September 15
50% (typical)May 7September 29
90% (likely)April 25October 13
Frost-free season (32°F, 50% chance)
145 days
Hard frost (28°F), last in spring, 50% chance after
April 28
Hard frost (28°F), first in fall, 50% chance before
October 8

The last 15 years (2006–2020 normals)

Typical last frost May 7 (same as the 30-year normal), typical first fall frost October 1 (2 days later). Frost-free season 146 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 Lake Wilson: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 19, 20% May 14, 30% May 11, 40% May 9, 50% May 7, 60% May 4, 70% May 2, 80% April 29, 90% April 25. Observed last spring frost in recent years: 2021 May 12, 2022 May 5, 2023 April 26, 2025 April 30, 2026 May 11.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 19May 7Apr 252021: May 122022: May 52023: April 262025: April 302026: May 11Fall at Lake Wilson: chance of a frost before this dateFall, chance of a frost before the date: 10% September 15, 20% September 20, 30% September 24, 40% September 27, 50% September 29, 60% October 2, 70% October 5, 80% October 8, 90% October 13. Observed first fall frost in recent years: 2022 October 8, 2023 October 10, 2025 October 6.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 15Sep 29Oct 132022: October 82023: October 102025: October 6
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 12incomplete record
2022May 5October 8
2023April 26October 10
2024incomplete recordincomplete record
2025April 30October 6
2026May 11season not over yet

What these dates mean

September 15 marks the cautious fall date for finishing the harvest of tender crops in Lake Wilson, carrying only a 10 % chance that a light frost has already arrived. The 50 % dates for light frost are May 7 in spring and September 29 in fall; at those points there is an even chance of a frost occurring later (spring) or earlier (fall). The hard-frost 50 % dates are April 28 in spring and October 8 in fall, and a hard frost at 28 °F can damage plants more severely than a light frost at 32 °F because it reaches temperatures that kill tissue.

For a cautious planting schedule, gardeners rely on the May 19 spring date, which carries a 10 % chance of a frost later than that day, and on the September 15 fall date to end tender-crop harvesting. Planting on April 25 or counting on crops through October 13 involves a 90 % chance of frost and is therefore a gamble.

How to read the probabilities

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

  • Spring: "10% after May 19" 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 15" 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 Lake Wilson, MNNumbered nearest stations: 1 — Pipestone, MN — 19 mi; 2 — Tracy, MN — 23 mi; 3 — Worthington, MN — 31 mi; 4 — Flandreau, SD — 32 mi; 5 — Marshall, MN — 34 mi.MNSDIA25 mi · 40 km1. Pipestone, MN — 19 mi12. Tracy, MN — 23 mi23. Worthington, MN — 31 mi34. Flandreau, SD — 32 mi45. Marshall, MN — 34 mi5
  1. Pipestone, MN 19 mi (30 km)
  2. Tracy, MN 23 mi (37 km)
  3. Worthington, MN 31 mi (49 km)
  4. Flandreau, SD 32 mi (52 km)
  5. Marshall, MN 34 mi (54 km)

Sources

* Hardiness zone 5a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 43.9983, -95.9494.