U.S. Frost Dates by Weather Station

NOAA station USC00394834 · South Dakota

Frost Dates for Lead, SD

NOAA weather station Lead (USC00394834), South Dakota · elevation 5112 ft (1558 m) · hardiness zone 5a*

  • Lower-risk planting dateafter June 1only 1 spring in 10 still has a frost later
  • Typical last frostMay 1850% chance of a frost after it
  • Typical first fall frostSeptember 2950% chance of a frost before it
  • Frost-free season133 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Lead, SDSpring: a frost after May 5 in 9 years out of 10, after May 18 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 15 in 1 year out of 10, before September 29 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 133 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 18First frost ~Sep 29Frost season at Lead, SDSpring: a frost after May 5 in 9 years out of 10, after May 18 in half of the years, after June 1 in 1 year out of 10. Fall: the first frost comes before September 15 in 1 year out of 10, before September 29 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 133 days.JFMAMJJASONDLast frost ~May 18First frost ~Sep 29
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 1September 15
50% (typical)May 18September 29
90% (likely)May 5October 13
Frost-free season (32°F, 50% chance)
133 days
Hard frost (28°F), last in spring, 50% chance after
May 6
Hard frost (28°F), first in fall, 50% chance before
October 7

The last 15 years (2006–2020 normals)

Typical last frost May 17 (1 day earlier than the 30-year normal), typical first fall frost October 1 (2 days later). Frost-free season 135 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 Lead: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 1, 20% May 28, 30% May 24, 40% May 21, 50% May 18, 60% May 16, 70% May 12, 80% May 9, 90% May 5. Observed last spring frost in recent years: 2021 May 31, 2022 May 22, 2023 May 1, 2024 June 19, 2025 May 22, 2026 May 20.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 1May 18May 52021: May 312022: May 222023: May 12024: June 192025: May 222026: May 20Fall at Lead: chance of a frost before this dateFall, chance of a frost before the date: 10% September 15, 20% September 20, 30% September 24, 40% September 27, 50% September 29, 60% October 1, 70% October 4, 80% October 8, 90% October 13. Observed first fall frost in recent years: 2021 October 12, 2022 October 7, 2023 October 6, 2024 October 1, 2025 October 7.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 15Sep 29Oct 132021: October 122022: October 72023: October 62024: October 12025: October 7
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 31October 12
2022May 22October 7
2023May 1October 6
2024June 19October 1
2025May 22October 7
2026May 20season not over yet

What these dates mean

The interval between the two 32°F 50% dates in Lead spans 133 days, defining the core planting window for tender crops.

In spring the median light-frost date is May 18; there is a 50% chance of a frost later than this date. Gardeners who prefer the cautious approach wait until June 1, which carries only a 10% chance of a later frost, while planting on May 5 would be a gamble with a 90% chance of frost. In fall the median light-frost date is September 29, meaning a 50% chance of a frost earlier than this date. The cautious September 15 date has just a 10% chance that frost has already arrived, whereas aiming for October 13 would be a gamble with a 90% chance of frost.

The hard-frost threshold is stricter: the 28°F 50% dates are May 6 and October 7, and a hard frost can damage plants that survive a light frost, so those dates signal a higher risk of injury.

How to read the probabilities

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

  • Spring: "10% after June 1" 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 15" 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 Lead, SDNumbered nearest stations: 1 — Spearfish, SD — 12 mi; 2 — near Sturgis, SD — 14 mi; 3 — Belle Fourche, SD — 23 mi; 4 — near Colonial Pine Hills, SD — 24 mi; 5 — near Blackhawk, SD — 28 mi.SDWYMT25 mi · 40 km1. Spearfish, SD — 12 mi12. near Sturgis, SD — 14 mi23. Belle Fourche, SD — 23 mi34. near Colonial Pine Hills, SD — 24 mi45. near Blackhawk, SD — 28 mi5
  1. Spearfish, SD 12 mi (19 km)
  2. near Sturgis, SD 14 mi (22 km)
  3. Belle Fourche, SD 23 mi (36 km)
  4. near Colonial Pine Hills, SD 24 mi (39 km)
  5. near Blackhawk, SD 28 mi (45 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: 44.3544, -103.743.