U.S. Frost Dates by Weather Station

NOAA station USC00235340 · Missouri

Frost Dates for Maryville, MO

NOAA weather station Maryville 2 E (USC00235340), Missouri · elevation 985 ft (300 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 3only 1 spring in 10 still has a frost later
  • Typical last frostApril 1950% chance of a frost after it
  • Typical first fall frostOctober 1750% chance of a frost before it
  • Frost-free season180 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Maryville, MOSpring: a frost after April 4 in 9 years out of 10, after April 19 in half of the years, after May 3 in 1 year out of 10. Fall: the first frost comes before October 2 in 1 year out of 10, before October 17 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 180 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 19First frost ~Oct 17Frost season at Maryville, MOSpring: a frost after April 4 in 9 years out of 10, after April 19 in half of the years, after May 3 in 1 year out of 10. Fall: the first frost comes before October 2 in 1 year out of 10, before October 17 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 180 days.JFMAMJJASONDLast frost ~Apr 19First frost ~Oct 17
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 2
50% (typical)April 19October 17
90% (likely)April 4October 30
Frost-free season (32°F, 50% chance)
180 days
Hard frost (28°F), last in spring, 50% chance after
April 8
Hard frost (28°F), first in fall, 50% chance before
October 27

The last 15 years (2006–2020 normals)

Typical last frost April 20 (1 day later than the 30-year normal), typical first fall frost October 18 (1 day later). Frost-free season 182 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 Maryville: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 3, 20% April 30, 30% April 26, 40% April 22, 50% April 19, 60% April 16, 70% April 13, 80% April 9, 90% April 4.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 3Apr 19Apr 4Fall at Maryville: chance of a frost before this dateFall, chance of a frost before the date: 10% October 2, 20% October 8, 30% October 12, 40% October 15, 50% October 17, 60% October 20, 70% October 23, 80% October 26, 90% October 30.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 2Oct 17Oct 30
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.

What these dates mean

The 180 days between the 50% dates in Maryville, Missouri, frame the central portion of the growing season. The 50% spring light-frost date is April 19 and the 50% fall light-frost date is October 17; each represents an even-odds point for a frost occurring.

For a cautious plan, tender crops are best set out after the May 3 date, which carries a 10 % chance of a later frost, while harvesting or finishing tender crops should be completed by October 2, the fall date with only a 10 % chance that a frost has already arrived.

Hard frost at 28 °F is more damaging than a light frost at 32 °F, so the April 8 and October 27 50% hard-frost dates mark a higher risk threshold for plants.

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 2" 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 Maryville, MONumbered nearest stations: 1 — Conception, MO — 11 mi; 2 — Bedford, IA — 23 mi; 3 — Clarinda, IA — 28 mi; 4 — Oregon, MO — 30 mi; 5 — Troy, KS — 38 mi.MOIANEKS25 mi · 40 km1. Conception, MO — 11 mi12. Bedford, IA — 23 mi23. Clarinda, IA — 28 mi34. Oregon, MO — 30 mi45. Troy, KS — 38 mi5
  1. Conception, MO 11 mi (17 km)
  2. Bedford, IA 23 mi (38 km)
  3. Clarinda, IA 28 mi (45 km)
  4. Oregon, MO 30 mi (48 km)
  5. Troy, KS 38 mi (61 km)

Sources

* Hardiness zone 5b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 40.3458, -94.8342.