U.S. Frost Dates by Weather Station

NOAA station USC00395544 · South Dakota

Frost Dates for Milesville, SD

NOAA weather station Milesville 5 NE (USC00395544), South Dakota · elevation 2237 ft (682 m) · hardiness zone 4b*

  • 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 250% chance of a frost before it
  • Frost-free season147 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Milesville, 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 17 in 1 year out of 10, before October 2 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 147 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 8First frost ~Oct 2Frost season at Milesville, 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 17 in 1 year out of 10, before October 2 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 147 days.JFMAMJJASONDLast frost ~May 8First 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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 22September 17
50% (typical)May 8October 2
90% (likely)April 27October 17
Frost-free season (32°F, 50% chance)
147 days
Hard frost (28°F), last in spring, 50% chance after
April 29
Hard frost (28°F), first in fall, 50% chance before
October 12

The last 15 years (2006–2020 normals)

Typical last frost May 9 (1 day later than the 30-year normal), typical first fall frost October 5 (3 days 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 Milesville: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 22, 20% May 18, 30% May 14, 40% May 11, 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, 2024 May 4, 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 22024: May 42025: April 292026: May 8Fall at Milesville: chance of a frost before this dateFall, chance of a frost before the date: 10% September 17, 20% September 23, 30% September 28, 40% September 30, 50% October 2, 60% October 5, 70% October 8, 80% October 12, 90% October 17. Observed first fall frost in recent years: 2021 October 14, 2022 October 7, 2023 October 7, 2024 October 1, 2025 October 13.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 17Oct 2Oct 172021: October 142022: October 72023: October 72024: 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 11October 14
2022May 22October 7
2023May 2October 7
2024May 4October 1
2025April 29October 13
2026May 8season not over yet

What these dates mean

Setting out tender crops on the early spring date of April 27 in Milesville is a gamble, carrying a 90% chance of a light frost later. The cautious spring date for tender crops is May 22, when only a 10% chance of a light frost remains.

For fall, the cautious date to finish harvesting tender crops is September 17, with only a 10% chance that a light frost has arrived earlier.

The 50% date of May 8 marks the point at which a light frost is equally likely to occur later, and the 50% date of October 2 marks the point at which a light frost is equally likely to have arrived earlier. Hard frost at 28°F, shown by the 50% dates of April 29 and October 12, can damage plants more severely than a 32°F light frost.

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 17" 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 Milesville, SDNumbered nearest stations: 1 — Dupree 15 SSE, SD — 25 mi; 2 — Philip, SD — 32 mi; 3 — Dupree, SD — 37 mi; 4 — Cottonwood, SD — 40 mi; 5 — Elm Springs, SD — 44 mi.SD25 mi · 40 km1. Dupree 15 SSE, SD — 25 mi12. Philip, SD — 32 mi23. Dupree, SD — 37 mi34. Cottonwood, SD — 40 mi45. Elm Springs, SD — 44 mi5
  1. Dupree 15 SSE, SD 25 mi (41 km)
  2. Philip, SD 32 mi (52 km)
  3. Dupree, SD 37 mi (59 km)
  4. Cottonwood, SD 40 mi (65 km)
  5. Elm Springs, SD 44 mi (71 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: 44.5172, -101.6183.