U.S. Frost Dates by Weather Station

NOAA station USC00216565 · Minnesota

Frost Dates for Pipestone, MN

NOAA weather station Pipestone (USC00216565), Minnesota · elevation 1705 ft (520 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 19only 1 spring in 10 still has a frost later
  • Typical last frostMay 450% chance of a frost after it
  • Typical first fall frostOctober 250% chance of a frost before it
  • Frost-free season152 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Pipestone, MNSpring: a frost after April 21 in 9 years out of 10, after May 4 in half of the years, after May 19 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 2 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 152 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 4First frost ~Oct 2Frost season at Pipestone, MNSpring: a frost after April 21 in 9 years out of 10, after May 4 in half of the years, after May 19 in 1 year out of 10. Fall: the first frost comes before September 20 in 1 year out of 10, before October 2 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 152 days.JFMAMJJASONDLast frost ~May 4First frost ~Oct 2
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 19September 20
50% (typical)May 4October 2
90% (likely)April 21October 16
Frost-free season (32°F, 50% chance)
152 days
Hard frost (28°F), last in spring, 50% chance after
April 25
Hard frost (28°F), first in fall, 50% chance before
October 12

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 6 (4 days later). Frost-free season 153 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 Pipestone: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 19, 20% May 13, 30% May 9, 40% May 6, 50% May 4, 60% May 2, 70% April 29, 80% April 26, 90% April 21. Observed last spring frost in recent years: 2021 May 11, 2022 April 27, 2023 May 3, 2024 April 25, 2025 May 3, 2026 May 11.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 19May 4Apr 212021: May 112022: April 272023: May 32024: April 252025: May 32026: May 11Fall at Pipestone: chance of a frost before this dateFall, chance of a frost before the date: 10% September 20, 20% September 24, 30% September 27, 40% September 30, 50% October 2, 60% October 5, 70% October 7, 80% October 11, 90% October 16. Observed first fall frost in recent years: 2021 October 16, 2022 October 7, 2023 October 7, 2024 October 1, 2025 September 6.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 20Oct 2Oct 162021: October 162022: October 72023: October 72024: October 12025: September 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 11October 16
2022April 27October 7
2023May 3October 7
2024April 25October 1
2025May 3September 6
2026May 11season not over yet

What these dates mean

The 152 days between the 32°F 50% dates of May 4 and October 2 mark the span in which a light frost is as likely as not for Pipestone gardeners. The May 4 and October 2 dates are not frost dates themselves; they simply indicate the median point where the probability of a 32°F frost reaches fifty percent. For a cautious spring schedule, the May 19 date carries only a ten percent chance of a later light frost and is used to set out tender crops, while the September 20 date, also with a ten percent chance of an earlier light frost, guides the safe finish of tender harvests in fall. The hard-frost 50% dates of April 25 and October 12 show that a 28°F frost can cause deeper plant injury than a light 32°F frost, making it a more critical concern for growers.

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 20" 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 Pipestone, MNNumbered nearest stations: 1 — Flandreau, SD — 14 mi; 2 — Lake Wilson, MN — 19 mi; 3 — Brookings, SD — 31 mi; 4 — Sioux Falls, SD — 36 mi; 5 — Tracy, MN — 38 mi.MNSDIA25 mi · 40 km1. Flandreau, SD — 14 mi12. Lake Wilson, MN — 19 mi23. Brookings, SD — 31 mi34. Sioux Falls, SD — 36 mi45. Tracy, MN — 38 mi5
  1. Flandreau, SD 14 mi (22 km)
  2. Lake Wilson, MN 19 mi (30 km)
  3. Brookings, SD 31 mi (49 km)
  4. Sioux Falls, SD 36 mi (57 km)
  5. Tracy, MN 38 mi (61 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: 44.0139, -96.3258.