U.S. Frost Dates by Weather Station

NOAA station USC00395406 · South Dakota

Frost Dates for McLaughlin, SD

NOAA weather station McLaughlin (USC00395406), South Dakota · elevation 2001 ft (610 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 25only 1 spring in 10 still has a frost later
  • Typical last frostMay 1250% chance of a frost after it
  • Typical first fall frostSeptember 2850% chance of a frost before it
  • Frost-free season137 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at McLaughlin, SDSpring: a frost after May 2 in 9 years out of 10, after May 12 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 16 in 1 year out of 10, before September 28 in half of the years, before October 9 in 9 years out of 10. Typical frost-free season: 137 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 12First frost ~Sep 28Frost season at McLaughlin, SDSpring: a frost after May 2 in 9 years out of 10, after May 12 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 16 in 1 year out of 10, before September 28 in half of the years, before October 9 in 9 years out of 10. Typical frost-free season: 137 days.JFMAMJJASONDLast frost ~May 12First frost ~Sep 28
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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 25September 16
50% (typical)May 12September 28
90% (likely)May 2October 9
Frost-free season (32°F, 50% chance)
137 days
Hard frost (28°F), last in spring, 50% chance after
May 3
Hard frost (28°F), first in fall, 50% chance before
October 5

The last 15 years (2006–2020 normals)

Typical last frost May 12 (same as the 30-year normal), typical first fall frost October 2 (4 days later). Frost-free season 142 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 McLaughlin: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 25, 20% May 21, 30% May 18, 40% May 14, 50% May 12, 60% May 9, 70% May 7, 80% May 4, 90% May 2. Observed last spring frost in recent years: 2022 May 22, 2023 May 3, 2024 May 4, 2025 April 30, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 25May 12May 22022: May 222023: May 32024: May 42025: April 302026: May 7Fall at McLaughlin: chance of a frost before this dateFall, chance of a frost before the date: 10% September 16, 20% September 20, 30% September 23, 40% September 25, 50% September 28, 60% September 30, 70% October 2, 80% October 5, 90% October 9. Observed first fall frost in recent years: 2022 October 7, 2023 October 7, 2024 October 1, 2025 October 6.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 16Sep 28Oct 92022: October 72023: October 72024: October 12025: 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
2021no datano data
2022May 22October 7
2023May 3October 7
2024May 4October 1
2025April 30October 6
2026May 7season not over yet

What these dates mean

May 25, the cautious spring date with a 10 % chance of a later frost, gives a gardener a reliable point to set out tender crops.

The 50% date is May 12; at that moment the chance of a light frost later is even. The 50% date is September 28; the chance of a light frost earlier is even. For hard frost, the 50% date is May 3 and the 50% date is October 5, marking the median moments when temperatures reach 28 °F. The cautious fall date, September 16, carries only a 10 % chance that a light frost has already arrived, allowing a gardener to finish harvesting tender crops with minimal risk.

A hard frost at 28 °F can damage plant tissue that usually survives a light frost at 32 °F.

How to read the probabilities

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

  • Spring: "10% after May 25" 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 16" 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 McLaughlin, SDNumbered nearest stations: 1 — Pollock, SD — 26 mi; 2 — Timber Lake, SD — 30 mi; 3 — Selby, SD — 43 mi; 4 — Hazelton, ND — 54 mi; 5 — Pretty Rock, ND — 56 mi.NDSD25 mi · 40 km1. Pollock, SD — 26 mi12. Timber Lake, SD — 30 mi23. Selby, SD — 43 mi34. Hazelton, ND — 54 mi45. Pretty Rock, ND — 56 mi5
  1. Pollock, SD 26 mi (41 km)
  2. Timber Lake, SD 30 mi (48 km)
  3. Selby, SD 43 mi (69 km)
  4. Hazelton, ND 54 mi (86 km)
  5. Pretty Rock, ND 56 mi (90 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: 45.8133, -100.8072.