U.S. Frost Dates by Weather Station

NOAA station USW00014944 · South Dakota

Frost Dates for Sioux Falls, SD

NOAA weather station Sioux Falls (USW00014944), South Dakota · elevation 1430 ft (436 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 14only 1 spring in 10 still has a frost later
  • Typical last frostMay 150% chance of a frost after it
  • Typical first fall frostOctober 650% chance of a frost before it
  • Frost-free season157 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Sioux Falls, SDSpring: a frost after April 18 in 9 years out of 10, after May 1 in half of the years, after May 14 in 1 year out of 10. Fall: the first frost comes before September 23 in 1 year out of 10, before October 6 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 157 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 1First frost ~Oct 6Frost season at Sioux Falls, SDSpring: a frost after April 18 in 9 years out of 10, after May 1 in half of the years, after May 14 in 1 year out of 10. Fall: the first frost comes before September 23 in 1 year out of 10, before October 6 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 157 days.JFMAMJJASONDLast frost ~May 1First frost ~Oct 6
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 14September 23
50% (typical)May 1October 6
90% (likely)April 18October 20
Frost-free season (32°F, 50% chance)
157 days
Hard frost (28°F), last in spring, 50% chance after
April 22
Hard frost (28°F), first in fall, 50% chance before
October 17

The last 15 years (2006–2020 normals)

Typical last frost May 1 (same as the 30-year normal), typical first fall frost October 10 (4 days later). Frost-free season 161 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 Sioux Falls: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 14, 20% May 10, 30% May 6, 40% May 3, 50% May 1, 60% April 29, 70% April 26, 80% April 23, 90% April 18. Observed last spring frost in recent years: 2021 May 11, 2022 April 26, 2023 May 3, 2024 April 21, 2025 April 21, 2026 May 20.Spring: last frostChance of a frost after this date10%50%90%May 1May 14May 1Apr 182021: May 112022: April 262023: May 32024: April 212025: April 212026: May 20Fall at Sioux Falls: chance of a frost before this dateFall, chance of a frost before the date: 10% September 23, 20% September 27, 30% September 30, 40% October 3, 50% October 6, 60% October 9, 70% October 12, 80% October 15, 90% October 20. Observed first fall frost in recent years: 2021 October 23, 2022 October 7, 2023 October 7, 2024 October 14, 2025 October 21.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 23Oct 6Oct 202021: October 232022: October 72023: October 72024: October 142025: October 21
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 23
2022April 26October 7
2023May 3October 7
2024April 21October 14
2025April 21October 21
2026May 20season not over yet

What these dates mean

May 14 is the cautious spring light-frost date, giving a gardener the confidence to set out tender crops after that day. The early-season gamble would be to plant before April 18, when a frost is still likely, while the median light-frost date of May 1 simply marks the point of equal odds for a frost. In the fall, September 23 serves as the cautious date for finishing tender crops, whereas planting after October 20 would carry a high risk of a frost. The median light-frost date of October 6 similarly represents an even chance of a frost later in the season.

April 22 and October 17 are the 50% hard-frost dates, each indicating a 50-50 chance that a hard frost at 28°F has occurred. A hard frost matters more than a light frost because the lower temperature can damage plants that would otherwise survive 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 14" 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 23" 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 Sioux Falls, SDNumbered nearest stations: 1 — Rock Rapids, IA — 30 mi; 2 — Flandreau, SD — 33 mi; 3 — Madison, SD — 33 mi; 4 — Pipestone, MN — 36 mi; 5 — Centerville, SD — 39 mi.SDMNIA25 mi · 40 km1. Rock Rapids, IA — 30 mi12. Flandreau, SD — 33 mi23. Madison, SD — 33 mi34. Pipestone, MN — 36 mi45. Centerville, SD — 39 mi5
  1. Rock Rapids, IA 30 mi (48 km)
  2. Flandreau, SD 33 mi (53 km)
  3. Madison, SD 33 mi (53 km)
  4. Pipestone, MN 36 mi (57 km)
  5. Centerville, SD 39 mi (62 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: 43.5878, -96.7289.