U.S. Frost Dates by Weather Station

NOAA station USC00392647 · South Dakota

Frost Dates for Elm Springs, SD

NOAA weather station Elm Springs 3 ESE (USC00392647), South Dakota · elevation 2645 ft (806 m) · hardiness zone 5a*

  • 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 season146 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Elm Springs, SDSpring: a frost after April 27 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 18 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: 146 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 8First frost ~Oct 3Frost season at Elm Springs, SDSpring: a frost after April 27 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 18 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: 146 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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 22September 18
50% (typical)May 8October 3
90% (likely)April 27October 16
Frost-free season (32°F, 50% chance)
146 days
Hard frost (28°F), last in spring, 50% chance after
April 30
Hard frost (28°F), first in fall, 50% chance before
October 11

The last 15 years (2006–2020 normals)

Typical last frost May 8 (same as the 30-year normal), typical first fall frost October 4 (1 day later). Frost-free season 148 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 Elm Springs: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 22, 20% May 16, 30% May 13, 40% May 10, 50% May 8, 60% May 6, 70% May 4, 80% May 1, 90% April 27. Observed last spring frost in recent years: 2021 May 11, 2022 May 22, 2023 May 2, 2025 April 29, 2026 May 8.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 22May 8Apr 272021: May 112022: May 222023: May 22025: April 292026: May 8Fall at Elm Springs: chance of a frost before this dateFall, chance of a frost before the date: 10% September 18, 20% September 24, 30% September 28, 40% September 30, 50% October 3, 60% October 5, 70% October 8, 80% October 12, 90% October 16. Observed first fall frost in recent years: 2021 October 14, 2022 October 8, 2023 October 7, 2024 October 15, 2025 October 13.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 18Oct 3Oct 162021: October 142022: October 82023: October 72024: October 152025: 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 11October 14
2022May 22October 8
2023May 2October 7
2024incomplete recordOctober 15
2025April 29October 13
2026May 8season not over yet

What these dates mean

May 22 is the cautious spring light-frost date for Elm Springs, offering only a 10 % chance that a frost will occur later and therefore marking the day a gardener can set out tender crops with low risk. The 50 % date in spring is May 8; there is a 50 % chance of a frost later than this date. The median hard-frost date in spring is April 30, indicating when a 28 °F frost becomes equally likely as not.

September 18 is the cautious fall light-frost date, with only a 10 % chance that a frost has arrived earlier, so it is the day a gardener can finish harvesting tender crops with minimal risk. The 50 % date in fall is October 3; there is a 50 % chance of a frost earlier than this date. The median hard-frost date in fall is October 11. Because a hard frost at 28 °F can damage plants that survive a 32 °F light frost, it represents a greater threat to tender crops.

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 18" 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 Elm Springs, SDNumbered nearest stations: 1 — Red Owl, SD — 27 mi; 2 — Rapid City (Airport), SD — 35 mi; 3 — Maurine, SD — 38 mi; 4 — Cottonwood, SD — 39 mi; 5 — near Blackhawk, SD — 43 mi.WY25 mi · 40 km1. Red Owl, SD — 27 mi12. Rapid City (Airport), SD — 35 mi23. Maurine, SD — 38 mi34. Cottonwood, SD — 39 mi45. near Blackhawk, SD — 43 mi5
  1. Red Owl, SD 27 mi (43 km)
  2. Rapid City (Airport), SD 35 mi (56 km)
  3. Maurine, SD 38 mi (61 km)
  4. Cottonwood, SD 39 mi (63 km)
  5. near Blackhawk, SD 43 mi (69 km)

Sources

* Hardiness zone 5a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 44.3186, -102.4683.