U.S. Frost Dates by Weather Station

NOAA station USC00230608 · Missouri

Frost Dates for Bethany, MO

NOAA weather station Bethany (USC00230608), Missouri · elevation 949 ft (289 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 3only 1 spring in 10 still has a frost later
  • Typical last frostApril 1650% chance of a frost after it
  • Typical first fall frostOctober 2250% chance of a frost before it
  • Frost-free season186 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Bethany, MOSpring: a frost after April 1 in 9 years out of 10, after April 16 in half of the years, after May 3 in 1 year out of 10. Fall: the first frost comes before October 6 in 1 year out of 10, before October 22 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 186 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 16First frost ~Oct 22Frost season at Bethany, MOSpring: a frost after April 1 in 9 years out of 10, after April 16 in half of the years, after May 3 in 1 year out of 10. Fall: the first frost comes before October 6 in 1 year out of 10, before October 22 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 186 days.JFMAMJJASONDLast frost ~Apr 16First frost ~Oct 22
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 3October 6
50% (typical)April 16October 22
90% (likely)April 1November 2
Frost-free season (32°F, 50% chance)
186 days
Hard frost (28°F), last in spring, 50% chance after
April 5
Hard frost (28°F), first in fall, 50% chance before
October 31

The last 15 years (2006–2020 normals)

Typical last frost April 17 (1 day later than the 30-year normal), typical first fall frost October 22. Frost-free season 187 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 Bethany: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 3, 20% April 27, 30% April 23, 40% April 19, 50% April 16, 60% April 13, 70% April 9, 80% April 5, 90% April 1. Observed last spring frost in recent years: 2021 April 23, 2022 April 27, 2023 April 24.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 3Apr 16Apr 12021: April 232022: April 272023: April 24Fall at Bethany: chance of a frost before this dateFall, chance of a frost before the date: 10% October 6, 20% October 13, 30% October 16, 40% October 19, 50% October 22, 60% October 24, 70% October 27, 80% October 30, 90% November 2. Observed first fall frost in recent years: 2021 November 2, 2022 October 9, 2023 October 28.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 6Oct 22Nov 22021: November 22022: October 92023: October 28
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
2021April 23November 2
2022April 27October 9
2023April 24October 28
2024incomplete recordno data
2025no datano data
2026no dataseason not over yet

What these dates mean

Setting out tender crops on April 1 in Bethany is a gamble, because there is a 90% chance of a light frost later than this date. The cautious spring date for planting tender crops is May 3, when only a 10% chance of a frost remains.

The 50% date of April 16 carries a 50% chance of a light frost later than this date, marking the midpoint of the spring risk period. In the fall, October 22 carries a 50% chance of a light frost earlier than this date, marking the midpoint of the autumn risk period. The cautious fall date for finishing tender crops is October 6, with only a 10% chance that a frost has already arrived. The median hard-frost dates are April 5 and October 31, indicating when a 28 °F frost is equally likely to have occurred or not.

A hard frost at 28 °F can damage plants that 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 3" 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 October 6" 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 Bethany, MONumbered nearest stations: 1 — Spickard, MO — 16 mi; 2 — Lamoni, IA — 26 mi; 3 — Amity, MO — 31 mi; 4 — Mount Ayr, IA — 33 mi; 5 — Conception, MO — 35 mi.MOKSNE25 mi · 40 km1. Spickard, MO — 16 mi12. Lamoni, IA — 26 mi23. Amity, MO — 31 mi34. Mount Ayr, IA — 33 mi45. Conception, MO — 35 mi5
  1. Spickard, MO 16 mi (26 km)
  2. Lamoni, IA 26 mi (41 km)
  3. Amity, MO 31 mi (50 km)
  4. Mount Ayr, IA 33 mi (53 km)
  5. Conception, MO 35 mi (56 km)

Sources

* Hardiness zone 6a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 40.2575, -94.0269.