U.S. Frost Dates by Weather Station

NOAA station USC00395481 · South Dakota

Frost Dates for Menno, SD

NOAA weather station Menno (USC00395481), South Dakota · elevation 1332 ft (406 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 450% chance of a frost before it
  • Frost-free season156 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Menno, SDSpring: a frost after April 17 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 21 in 1 year out of 10, before October 4 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 156 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 1First frost ~Oct 4Frost season at Menno, SDSpring: a frost after April 17 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 21 in 1 year out of 10, before October 4 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 156 days.JFMAMJJASONDLast frost ~May 1First frost ~Oct 4
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 14September 21
50% (typical)May 1October 4
90% (likely)April 17October 17
Frost-free season (32°F, 50% chance)
156 days
Hard frost (28°F), last in spring, 50% chance after
April 22
Hard frost (28°F), first in fall, 50% chance before
October 13

The last 15 years (2006–2020 normals)

Typical last frost May 1 (same as the 30-year normal), typical first fall frost October 7 (3 days later). Frost-free season 160 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 Menno: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 14, 20% May 9, 30% May 6, 40% May 4, 50% May 1, 60% April 29, 70% April 26, 80% April 22, 90% April 17. Observed last spring frost in recent years: 2021 May 6, 2022 May 22, 2023 May 3, 2024 April 24, 2025 April 21, 2026 May 6.Spring: last frostChance of a frost after this date10%50%90%May 1May 14May 1Apr 172021: May 62022: May 222023: May 32024: April 242025: April 212026: May 6Fall at Menno: chance of a frost before this dateFall, chance of a frost before the date: 10% September 21, 20% September 26, 30% September 29, 40% October 1, 50% October 4, 60% October 6, 70% October 10, 80% October 13, 90% October 17. Observed first fall frost in recent years: 2021 October 15, 2022 October 7, 2023 October 7, 2024 October 14, 2025 October 22.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 21Oct 4Oct 172021: October 152022: October 72023: October 72024: October 142025: October 22
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 6October 15
2022May 22October 7
2023May 3October 7
2024April 24October 14
2025April 21October 22
2026May 6season not over yet

What these dates mean

The 156 days between the two 32°F 50% dates—May 1 and October 4—frame the period in Menno when light frosts are equally likely to have occurred or not.

Gardeners note that the 50% date is May 1, when there is a 50 % chance of a light frost later, and the 50% date is October 4, when there is a 50 % chance of a light frost earlier. The cautious spring date for setting out tender crops is May 14, which carries only a 10 % chance of a later frost, while the cautious fall date to finish harvesting tender crops is September 21, which carries only a 10 % chance of an earlier frost. The median hard-frost dates are April 22 and October 13. A hard frost at 28°F can freeze plant tissue that often survives 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 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 Menno, SDNumbered nearest stations: 1 — Bridgewater, SD — 22 mi; 2 — Tyndall, SD — 23 mi; 3 — Yankton, SD — 27 mi; 4 — Alexandria, SD — 31 mi; 5 — Crofton, NE — 35 mi.SDNEIAMN25 mi · 40 km1. Bridgewater, SD — 22 mi12. Tyndall, SD — 23 mi23. Yankton, SD — 27 mi34. Alexandria, SD — 31 mi45. Crofton, NE — 35 mi5
  1. Bridgewater, SD 22 mi (36 km)
  2. Tyndall, SD 23 mi (36 km)
  3. Yankton, SD 27 mi (43 km)
  4. Alexandria, SD 31 mi (50 km)
  5. Crofton, NE 35 mi (56 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: 43.2358, -97.5714.