U.S. Frost Dates by Weather Station

NOAA station USC00395638 · South Dakota

Frost Dates for Mission, SD

NOAA weather station Mission 14 S (USC00395638), South Dakota · elevation 2810 ft (857 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 25only 1 spring in 10 still has a frost later
  • Typical last frostMay 1150% chance of a frost after it
  • Typical first fall frostOctober 250% chance of a frost before it
  • Frost-free season145 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Mission, SDSpring: a frost after April 30 in 9 years out of 10, after May 11 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 2 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 145 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 11First frost ~Oct 2Frost season at Mission, SDSpring: a frost after April 30 in 9 years out of 10, after May 11 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 2 in half of the years, before October 16 in 9 years out of 10. Typical frost-free season: 145 days.JFMAMJJASONDLast frost ~May 11First 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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 25September 21
50% (typical)May 11October 2
90% (likely)April 30October 16
Frost-free season (32°F, 50% chance)
145 days
Hard frost (28°F), last in spring, 50% chance after
May 1
Hard frost (28°F), first in fall, 50% chance before
October 13

The last 15 years (2006–2020 normals)

Typical last frost May 12 (1 day later than the 30-year normal), typical first fall frost October 4 (2 days later). Frost-free season 144 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 Mission: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 25, 20% May 20, 30% May 16, 40% May 13, 50% May 11, 60% May 8, 70% May 5, 80% May 3, 90% April 30. Observed last spring frost in recent years: 2021 May 12, 2022 May 24, 2023 May 3, 2024 May 4, 2025 April 20, 2026 May 20.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 25May 11Apr 302021: May 122022: May 242023: May 32024: May 42025: April 202026: May 20Fall at Mission: chance of a frost before this dateFall, chance of a frost before the date: 10% September 21, 20% September 25, 30% September 28, 40% September 30, 50% October 2, 60% October 5, 70% October 8, 80% October 12, 90% October 16. 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 21Oct 2Oct 162021: 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 12October 14
2022May 24October 7
2023May 3October 7
2024May 4October 1
2025April 20October 13
2026May 20season not over yet

What these dates mean

The cautious fall date in Mission for finishing the harvest is September 21, when there is only a 10 % chance that a light frost has arrived.

The cautious spring date for setting out tender crops is May 25, with a 10 % chance of a frost later than this date; planting on April 30 would be a gamble, because the chance then is 90 %. The 50% light-frost date in spring is May 11, which marks a 50 % chance of a frost later than this date. The 50% light-frost date in fall is October 2, which marks a 50 % chance of a frost earlier than this date. Hard frost (28 °F) matters more than light frost because the lower temperature can injure plants that would survive 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 25" 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 21" 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 Mission, SDNumbered nearest stations: 1 — near Valentine, NE — 16 mi; 2 — Springview, NE — 46 mi; 3 — Murdo, SD — 54 mi; 4 — Ainsworth, NE — 54 mi; 5 — Gregory, SD — 60 mi.SDNE25 mi · 40 km1. near Valentine, NE — 16 mi12. Springview, NE — 46 mi23. Murdo, SD — 54 mi34. Ainsworth, NE — 54 mi45. Gregory, SD — 60 mi5
  1. near Valentine, NE 16 mi (26 km)
  2. Springview, NE 46 mi (74 km)
  3. Murdo, SD 54 mi (87 km)
  4. Ainsworth, NE 54 mi (88 km)
  5. Gregory, SD 60 mi (96 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: 43.1122, -100.6111.