U.S. Frost Dates by Weather Station

NOAA station USC00217184 · Minnesota

Frost Dates for Rushford, MN

NOAA weather station Rushford (USC00217184), Minnesota · elevation 770 ft (235 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 22only 1 spring in 10 still has a frost later
  • Typical last frostMay 850% chance of a frost after it
  • Typical first fall frostOctober 350% chance of a frost before it
  • Frost-free season147 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Rushford, MNSpring: a frost after April 25 in 9 years out of 10, after May 8 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 3 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 147 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 8First frost ~Oct 3Frost season at Rushford, MNSpring: a frost after April 25 in 9 years out of 10, after May 8 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 3 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 147 days.JFMAMJJASONDLast frost ~May 8First frost ~Oct 3
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 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 22September 21
50% (typical)May 8October 3
90% (likely)April 25October 16
Frost-free season (32°F, 50% chance)
147 days
Hard frost (28°F), last in spring, 50% chance after
April 29
Hard frost (28°F), first in fall, 50% chance before
October 12

The last 15 years (2006–2020 normals)

Typical last frost May 5 (3 days earlier than the 30-year normal), typical first fall frost October 6 (3 days later). Frost-free season 152 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 Rushford: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 22, 20% May 17, 30% May 14, 40% May 11, 50% May 8, 60% May 5, 70% May 2, 80% April 29, 90% April 25. Observed last spring frost in recent years: 2021 May 12, 2022 May 5, 2023 May 4, 2024 April 26, 2025 April 27, 2026 May 12.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 22May 8Apr 252021: May 122022: May 52023: May 42024: April 262025: April 272026: May 12Fall at Rushford: chance of a frost before this dateFall, chance of a frost before the date: 10% September 21, 20% September 25, 30% September 28, 40% October 1, 50% October 3, 60% October 5, 70% October 7, 80% October 11, 90% October 16. Observed first fall frost in recent years: 2021 October 17, 2022 September 28, 2023 October 10, 2024 October 7, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 21Oct 3Oct 162021: October 172022: September 282023: October 102024: October 72025: 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 12October 17
2022May 5September 28
2023May 4October 10
2024April 26October 7
2025April 27October 23
2026May 12season not over yet

What these dates mean

The 147 days between the 50% dates of May 8 and October 3 in Rushford frame the period when light frost is equally likely to have occurred or not.

The 50% dates themselves are not frost dates; they simply mark the point at which a gardener faces a 50 % chance of a light frost later in spring or earlier in fall. For a cautious plan, tender crops are best placed outdoors after the May 22 date, which carries only a 10 % chance of a later frost, and are harvested before the September 21 date, which also carries only a 10 % chance of an earlier frost.

Hard frosts at 28 °F, whose 50% median falls on April 29 in spring and October 12 in fall, can damage plants more severely than the 32 °F light frosts.

How to read the probabilities

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

  • Spring: "10% after May 22" 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 21" 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 Rushford, MNNumbered nearest stations: 1 — Caledonia, MN — 17 mi; 2 — Preston, MN — 19 mi; 3 — near Winona, MN — 20 mi; 4 — near Trempealeau, WI — 21 mi; 5 — La Crosse, WI — 25 mi.WIMN25 mi · 40 km1. Caledonia, MN — 17 mi12. Preston, MN — 19 mi23. near Winona, MN — 20 mi34. near Trempealeau, WI — 21 mi45. La Crosse, WI — 25 mi5
  1. Caledonia, MN 17 mi (28 km)
  2. Preston, MN 19 mi (30 km)
  3. near Winona, MN 20 mi (32 km)
  4. near Trempealeau, WI 21 mi (33 km)
  5. La Crosse, WI 25 mi (41 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: 43.8053, -91.75.