U.S. Frost Dates by Weather Station

NOAA station USC00231822 · Missouri

Frost Dates for Conception, MO

NOAA weather station Conception (USC00231822), Missouri · elevation 1108 ft (338 m) · hardiness zone 6a*

  • Lower-risk planting dateafter April 30only 1 spring in 10 still has a frost later
  • Typical last frostApril 1750% chance of a frost after it
  • Typical first fall frostOctober 2050% chance of a frost before it
  • Frost-free season184 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Conception, MOSpring: a frost after April 3 in 9 years out of 10, after April 17 in half of the years, after April 30 in 1 year out of 10. Fall: the first frost comes before October 3 in 1 year out of 10, before October 20 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 184 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 17First frost ~Oct 20Frost season at Conception, MOSpring: a frost after April 3 in 9 years out of 10, after April 17 in half of the years, after April 30 in 1 year out of 10. Fall: the first frost comes before October 3 in 1 year out of 10, before October 20 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 184 days.JFMAMJJASONDLast frost ~Apr 17First frost ~Oct 20
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)April 30October 3
50% (typical)April 17October 20
90% (likely)April 3November 2
Frost-free season (32°F, 50% chance)
184 days
Hard frost (28°F), last in spring, 50% chance after
April 8
Hard frost (28°F), first in fall, 50% chance before
October 30

The last 15 years (2006–2020 normals)

Typical last frost April 18 (1 day later than the 30-year normal), typical first fall frost October 23 (3 days later). Frost-free season 188 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 Conception: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 30, 20% April 26, 30% April 23, 40% April 20, 50% April 17, 60% April 14, 70% April 11, 80% April 8, 90% April 3. Observed last spring frost in recent years: 2021 April 22, 2022 April 20, 2023 April 23, 2024 March 28, 2026 March 29.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 30Apr 17Apr 32021: April 222022: April 202023: April 232024: March 282026: March 29Fall at Conception: chance of a frost before this dateFall, chance of a frost before the date: 10% October 3, 20% October 10, 30% October 14, 40% October 17, 50% October 20, 60% October 23, 70% October 26, 80% October 29, 90% November 2. Observed first fall frost in recent years: 2021 November 3, 2022 October 17, 2023 October 28, 2024 November 21, 2025 November 9.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 3Oct 20Nov 22021: November 32022: October 172023: October 282024: November 212025: November 9
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 22November 3
2022April 20October 17
2023April 23October 28
2024March 28November 21
2025incomplete recordNovember 9
2026March 29season not over yet

What these dates mean

The 184 days between the 50% dates in Conception give the length of the period when light frost is equally likely to have occurred or not. The 50% dates—April 17 in spring and October 20 in fall—mark the median point where the chance of a light frost is 50 %, and they are not frost dates themselves.

For a cautious plan, tender crops should be set out after the spring cautious date of April 30, which carries only a 10 % chance of a later frost, and should be finished by the fall cautious date of October 3, which carries only a 10 % chance of an earlier frost. The spring gamble date is April 3 with a 90 % chance of a later frost, and the fall gamble date is November 2 with a 90 % chance of an earlier frost.

The 50% hard-frost dates are April 8 and October 30; a hard frost at 28 °F can damage plants that survive a light frost at 32 °F, so it matters more.

How to read the probabilities

The dates are probabilities from 30 years of weather, not a forecast for this year.

  • Spring: "10% after April 30" 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 3" 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 Conception, MONumbered nearest stations: 1 — Maryville, MO — 11 mi; 2 — Amity, MO — 30 mi; 3 — Bedford, IA — 30 mi; 4 — Oregon, MO — 30 mi; 5 — Bethany, MO — 35 mi.MOIAKSNE25 mi · 40 km1. Maryville, MO — 11 mi12. Amity, MO — 30 mi23. Bedford, IA — 30 mi34. Oregon, MO — 30 mi45. Bethany, MO — 35 mi5
  1. Maryville, MO 11 mi (17 km)
  2. Amity, MO 30 mi (47 km)
  3. Bedford, IA 30 mi (48 km)
  4. Oregon, MO 30 mi (49 km)
  5. Bethany, 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: 40.2394, -94.6833.