U.S. Frost Dates by Weather Station

NOAA station USC00395325 · South Dakota

Frost Dates for Maurine, SD

NOAA weather station Maurine 12 SW (USC00395325), South Dakota · elevation 2629 ft (801 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 27only 1 spring in 10 still has a frost later
  • Typical last frostMay 1350% chance of a frost after it
  • Typical first fall frostSeptember 2850% chance of a frost before it
  • Frost-free season136 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Maurine, SDSpring: a frost after May 2 in 9 years out of 10, after May 13 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 13 in 1 year out of 10, before September 28 in half of the years, before October 10 in 9 years out of 10. Typical frost-free season: 136 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 13First frost ~Sep 28Frost season at Maurine, SDSpring: a frost after May 2 in 9 years out of 10, after May 13 in half of the years, after May 27 in 1 year out of 10. Fall: the first frost comes before September 13 in 1 year out of 10, before September 28 in half of the years, before October 10 in 9 years out of 10. Typical frost-free season: 136 days.JFMAMJJASONDLast frost ~May 13First 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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 27September 13
50% (typical)May 13September 28
90% (likely)May 2October 10
Frost-free season (32°F, 50% chance)
136 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 13 (same as the 30-year normal), typical first fall frost September 30 (2 days later). Frost-free season 137 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 Maurine: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 27, 20% May 23, 30% May 19, 40% May 16, 50% May 13, 60% May 11, 70% May 8, 80% May 5, 90% May 2. Observed last spring frost in recent years: 2021 May 12, 2022 May 22, 2023 May 2, 2024 May 4, 2025 May 17, 2026 May 8.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 27May 13May 22021: May 122022: May 222023: May 22024: May 42025: May 172026: May 8Fall at Maurine: chance of a frost before this dateFall, chance of a frost before the date: 10% September 13, 20% September 18, 30% September 22, 40% September 25, 50% September 28, 60% September 30, 70% October 3, 80% October 5, 90% October 10. Observed first fall frost in recent years: 2021 October 14, 2022 October 7, 2023 October 6, 2024 October 1, 2025 October 13.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 13Sep 28Oct 102021: October 142022: October 72023: October 62024: October 12025: October 13
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 14
2022May 22October 7
2023May 2October 6
2024May 4October 1
2025May 17October 13
2026May 8season not over yet

What these dates mean

May 27 is the cautious spring date, with only a 10% chance of a light frost later, and it lets a gardener schedule the first out-planting of tender crops.

The 50% date in spring is May 13; at that point the chance of a light frost is 50%, and the median 50% date in fall is September 28; at that point the chance of a light frost is 50%. These dates define the middle of the frost-free window for the 27-year record. The median hard-frost dates are May 3 and October 5, marking when a 28 °F event is as likely as not.

September 13 is the cautious fall date, carrying a 10% chance that a light frost has already arrived, so it is the latest sensible day to finish harvesting tender crops. A hard frost at 28 °F can damage plants that survive a light frost, making it a more critical threshold for garden planning.

How to read the probabilities

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

  • Spring: "10% after May 27" 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 13" 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 Maurine, SDNumbered nearest stations: 1 — Red Owl, SD — 12 mi; 2 — Elm Springs, SD — 38 mi; 3 — Newell, SD — 43 mi; 4 — Bison, SD — 46 mi; 5 — Dupree, SD — 49 mi.WYMT25 mi · 40 km1. Red Owl, SD — 12 mi12. Elm Springs, SD — 38 mi23. Newell, SD — 43 mi34. Bison, SD — 46 mi45. Dupree, SD — 49 mi5
  1. Red Owl, SD 12 mi (19 km)
  2. Elm Springs, SD 38 mi (61 km)
  3. Newell, SD 43 mi (70 km)
  4. Bison, SD 46 mi (74 km)
  5. Dupree, SD 49 mi (78 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: 44.8656, -102.5658.