U.S. Frost Dates by Weather Station

NOAA station USW00014925 · Minnesota

Frost Dates for Rochester, MN

NOAA weather station Rochester International Airport (USW00014925), Minnesota · elevation 1304 ft (398 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 13only 1 spring in 10 still has a frost later
  • Typical last frostApril 3050% chance of a frost after it
  • Typical first fall frostOctober 650% chance of a frost before it
  • Frost-free season159 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Rochester, MNSpring: a frost after April 15 in 9 years out of 10, after April 30 in half of the years, after May 13 in 1 year out of 10. Fall: the first frost comes before September 22 in 1 year out of 10, before October 6 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 159 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 30First frost ~Oct 6Frost season at Rochester, MNSpring: a frost after April 15 in 9 years out of 10, after April 30 in half of the years, after May 13 in 1 year out of 10. Fall: the first frost comes before September 22 in 1 year out of 10, before October 6 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 159 days.JFMAMJJASONDLast frost ~Apr 30First frost ~Oct 6
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 13September 22
50% (typical)April 30October 6
90% (likely)April 15October 20
Frost-free season (32°F, 50% chance)
159 days
Hard frost (28°F), last in spring, 50% chance after
April 18
Hard frost (28°F), first in fall, 50% chance before
October 17

The last 15 years (2006–2020 normals)

Typical last frost April 29 (1 day earlier than the 30-year normal), typical first fall frost October 11 (5 days later). Frost-free season 164 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 Rochester: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 13, 20% May 8, 30% May 5, 40% May 2, 50% April 30, 60% April 28, 70% April 24, 80% April 21, 90% April 15. Observed last spring frost in recent years: 2021 April 25, 2022 April 27, 2023 April 26, 2024 April 24, 2025 April 16, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 13Apr 30Apr 152021: April 252022: April 272023: April 262024: April 242025: April 162026: May 7Fall at Rochester: chance of a frost before this dateFall, chance of a frost before the date: 10% September 22, 20% September 27, 30% October 1, 40% October 4, 50% October 6, 60% October 9, 70% October 12, 80% October 16, 90% October 20. Observed first fall frost in recent years: 2021 October 21, 2022 October 7, 2023 October 10, 2024 October 14, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 22Oct 6Oct 202021: October 212022: October 72023: October 102024: October 142025: 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
2021April 25October 21
2022April 27October 7
2023April 26October 10
2024April 24October 14
2025April 16October 23
2026May 7season not over yet

What these dates mean

May 13 is the cautious spring date for Rochester, offering only a 10 % chance of a light frost later and letting a gardener schedule the first planting of tender crops with minimal risk. The same cautious principle applies in autumn on September 22, when there is just a 10 % chance that a light frost has arrived earlier, marking a reliable point to finish harvesting tender crops.

For a gardener, the 50 % dates indicate the point at which a light frost is equally likely to occur or not. In spring the median date is April 30, and in fall the median date is October 6; these dates serve as reference points for weighing risk but are not frost dates themselves. The hard-frost 50 % dates are April 18 in spring and October 17 in fall, and a hard frost at 28 °F can damage plants that would survive a light frost at 32 °F, making the colder threshold more consequential.

How to read the probabilities

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

  • Spring: "10% after May 13" 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 22" 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 Rochester, MNNumbered nearest stations: 1 — Grand Meadow, MN — 14 mi; 2 — Preston, MN — 26 mi; 3 — Zumbrota, MN — 29 mi; 4 — Austin, MN — 30 mi; 5 — Theilman, MN — 30 mi.MNWIIA25 mi · 40 km1. Grand Meadow, MN — 14 mi12. Preston, MN — 26 mi23. Zumbrota, MN — 29 mi34. Austin, MN — 30 mi45. Theilman, MN — 30 mi5
  1. Grand Meadow, MN 14 mi (23 km)
  2. Preston, MN 26 mi (42 km)
  3. Zumbrota, MN 29 mi (46 km)
  4. Austin, MN 30 mi (48 km)
  5. Theilman, MN 30 mi (48 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: 43.9042, -92.4917.