U.S. Frost Dates by Weather Station

NOAA station USC00211198 · Minnesota

Frost Dates for Caledonia, MN

NOAA weather station Caledonia (USC00211198), Minnesota · elevation 1166 ft (355 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 11only 1 spring in 10 still has a frost later
  • Typical last frostApril 2950% chance of a frost after it
  • Typical first fall frostOctober 1050% chance of a frost before it
  • Frost-free season165 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Caledonia, MNSpring: a frost after April 14 in 9 years out of 10, after April 29 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before September 28 in 1 year out of 10, before October 10 in half of the years, before October 24 in 9 years out of 10. Typical frost-free season: 165 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 29First frost ~Oct 10Frost season at Caledonia, MNSpring: a frost after April 14 in 9 years out of 10, after April 29 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before September 28 in 1 year out of 10, before October 10 in half of the years, before October 24 in 9 years out of 10. Typical frost-free season: 165 days.JFMAMJJASONDLast frost ~Apr 29First frost ~Oct 10
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 11September 28
50% (typical)April 29October 10
90% (likely)April 14October 24
Frost-free season (32°F, 50% chance)
165 days
Hard frost (28°F), last in spring, 50% chance after
April 18
Hard frost (28°F), first in fall, 50% chance before
October 23

The last 15 years (2006–2020 normals)

Typical last frost April 28 (1 day earlier than the 30-year normal), typical first fall frost October 13 (3 days later). Frost-free season 167 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 Caledonia: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 11, 20% May 7, 30% May 3, 40% May 1, 50% April 29, 60% April 26, 70% April 23, 80% April 19, 90% April 14. Observed last spring frost in recent years: 2021 May 11, 2022 May 4, 2023 April 27, 2024 April 25, 2025 April 17, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 11Apr 29Apr 142021: May 112022: May 42023: April 272024: April 252025: April 172026: May 7Fall at Caledonia: chance of a frost before this dateFall, chance of a frost before the date: 10% September 28, 20% October 1, 30% October 5, 40% October 8, 50% October 10, 60% October 13, 70% October 17, 80% October 20, 90% October 24. Observed first fall frost in recent years: 2021 October 22, 2022 October 9, 2023 October 11, 2024 October 16, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 28Oct 10Oct 242021: October 222022: October 92023: October 112024: October 162025: October 23
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 22
2022May 4October 9
2023April 27October 11
2024April 25October 16
2025April 17October 23
2026May 7season not over yet

What these dates mean

May 11 marks the cautious spring light-frost date in Caledonia; with only a 10 % chance of a frost later than this day, a gardener can set out tender crops. The median light-frost date, April 29, represents an even-odds point, while April 14 carries a 90 % chance and would be a gamble for early planting.

In the fall, September 28 is the cautious light-frost date, offering a 10 % chance of a frost earlier than this day and therefore signals the latest recommended harvest for tender crops. The median autumn light-frost date, October 10, is the 50 % point, and October 24 carries a 90 % chance, making late planting risky.

Hard frosts at 28 °F are more damaging than light frosts at 32 °F because they can kill tissue that survives a milder freeze; the 50 % hard-frost dates are April 18 in spring and October 23 in fall. The two 32°F 50 % dates are 165 days apart over the 28-year record.

How to read the probabilities

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

  • Spring: "10% after May 11" 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 28" 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 Caledonia, MNNumbered nearest stations: 1 — Genoa Dam 8, WI — 14 mi; 2 — Rushford, MN — 17 mi; 3 — La Crosse, WI — 21 mi; 4 — near Trempealeau, WI — 26 mi; 5 — Decorah, IA — 27 mi.WIMNIA25 mi · 40 km1. Genoa Dam 8, WI — 14 mi12. Rushford, MN — 17 mi23. La Crosse, WI — 21 mi34. near Trempealeau, WI — 26 mi45. Decorah, IA — 27 mi5
  1. Genoa Dam 8, WI 14 mi (23 km)
  2. Rushford, MN 17 mi (28 km)
  3. La Crosse, WI 21 mi (34 km)
  4. near Trempealeau, WI 26 mi (41 km)
  5. Decorah, IA 27 mi (43 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: 43.6308, -91.5028.