U.S. Frost Dates by Weather Station

NOAA station USW00014929 · South Dakota

Frost Dates for Aberdeen, SD

NOAA weather station Aberdeen (USW00014929), South Dakota · elevation 1302 ft (397 m) · hardiness zone 4a*

  • Lower-risk planting dateafter May 22only 1 spring in 10 still has a frost later
  • Typical last frostMay 950% chance of a frost after it
  • Typical first fall frostSeptember 2650% chance of a frost before it
  • Frost-free season139 daystypical year, 32°F
  • Hardiness zone4acalculated*

The year at a glance

Frost season at Aberdeen, SDSpring: a frost after April 27 in 9 years out of 10, after May 9 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 14 in 1 year out of 10, before September 26 in half of the years, before October 7 in 9 years out of 10. Typical frost-free season: 139 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 9First frost ~Sep 26Frost season at Aberdeen, SDSpring: a frost after April 27 in 9 years out of 10, after May 9 in half of the years, after May 22 in 1 year out of 10. Fall: the first frost comes before September 14 in 1 year out of 10, before September 26 in half of the years, before October 7 in 9 years out of 10. Typical frost-free season: 139 days.JFMAMJJASONDLast frost ~May 9First frost ~Sep 26
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.Today

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 14
50% (typical)May 9September 26
90% (likely)April 27October 7
Frost-free season (32°F, 50% chance)
139 days
Hard frost (28°F), last in spring, 50% chance after
April 30
Hard frost (28°F), first in fall, 50% chance before
October 4

The last 15 years (2006–2020 normals)

Typical last frost May 11 (2 days later than the 30-year normal), typical first fall frost October 1 (5 days later). Frost-free season 139 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 Aberdeen: 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 9, 60% May 6, 70% May 4, 80% April 30, 90% April 27. Observed last spring frost in recent years: 2021 May 12, 2022 May 22, 2023 May 3, 2024 May 5, 2025 May 3, 2026 May 20.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 22May 9Apr 272021: May 122022: May 222023: May 32024: May 52025: May 32026: May 20Fall at Aberdeen: chance of a frost before this dateFall, chance of a frost before the date: 10% September 14, 20% September 18, 30% September 21, 40% September 24, 50% September 26, 60% September 28, 70% October 1, 80% October 4, 90% October 7. Observed first fall frost in recent years: 2021 September 25, 2022 September 28, 2023 October 6, 2024 October 4, 2025 October 8.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 14Sep 26Oct 72021: September 252022: September 282023: October 62024: October 42025: October 8
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 12September 25
2022May 22September 28
2023May 3October 6
2024May 5October 4
2025May 3October 8
2026May 20season not over yet

What these dates mean

May 22 is the cautious spring light-frost date in Aberdeen; with only a 10 % chance of a frost later, a gardener can plan to set out tender crops after that day.

The 50 % light-frost dates—May 9 in spring and September 26 in fall—represent the point at which the odds of a frost are even; they are not frost dates themselves but help a gardener gauge risk. The cautious fall light-frost date is September 14, when there is only a 10 % chance a frost has arrived, marking a reasonable time to finish harvesting tender crops. The median hard-frost dates are April 30 in spring and October 4 in fall, and a hard frost (28 °F) can damage plant tissue more severely than a light frost (32 °F).

The interval between the spring 32°F 50% date of May 9 and the fall 32°F 50% date of September 26 covers 139 days, based on 29 years of record.

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 14" 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 Aberdeen, SDNumbered nearest stations: 1 — Columbia, SD — 19 mi; 2 — Mellette, SD — 22 mi; 3 — Ipswich, SD — 30 mi; 4 — Britton, SD — 39 mi; 5 — Webster, SD — 44 mi.ND25 mi · 40 km1. Columbia, SD — 19 mi12. Mellette, SD — 22 mi23. Ipswich, SD — 30 mi34. Britton, SD — 39 mi45. Webster, SD — 44 mi5
  1. Columbia, SD 19 mi (31 km)
  2. Mellette, SD 22 mi (36 km)
  3. Ipswich, SD 30 mi (49 km)
  4. Britton, SD 39 mi (64 km)
  5. Webster, SD 44 mi (71 km)

Sources

* Hardiness zone 4a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 45.4558, -98.4131.