U.S. Frost Dates by Weather Station

NOAA station USW00003966 · Missouri

Frost Dates for St. Louis (Spirit of St. Louis Airport), MO

NOAA weather station St. Louis Spirit of St. Louis Airport (USW00003966), Missouri · elevation 462 ft (141 m) · hardiness zone 6b*

  • Lower-risk planting dateafter April 27only 1 spring in 10 still has a frost later
  • Typical last frostApril 1250% chance of a frost after it
  • Typical first fall frostOctober 2350% chance of a frost before it
  • Frost-free season193 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at St. Louis (Spirit of St. Louis Airport), MOSpring: a frost after March 28 in 9 years out of 10, after April 12 in half of the years, after April 27 in 1 year out of 10. Fall: the first frost comes before October 11 in 1 year out of 10, before October 23 in half of the years, before November 5 in 9 years out of 10. Typical frost-free season: 193 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 12First frost ~Oct 23Frost season at St. Louis (Spirit of St. Louis Airport), MOSpring: a frost after March 28 in 9 years out of 10, after April 12 in half of the years, after April 27 in 1 year out of 10. Fall: the first frost comes before October 11 in 1 year out of 10, before October 23 in half of the years, before November 5 in 9 years out of 10. Typical frost-free season: 193 days.JFMAMJJASONDLast frost ~Apr 12First frost ~Oct 23
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 27October 11
50% (typical)April 12October 23
90% (likely)March 28November 5
Frost-free season (32°F, 50% chance)
193 days
Hard frost (28°F), last in spring, 50% chance after
March 31
Hard frost (28°F), first in fall, 50% chance before
November 3

The last 15 years (2006–2020 normals)

Typical last frost April 12 (same as the 30-year normal), typical first fall frost October 23. Frost-free season 192 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 St. Louis (Spirit of St. Louis Airport): chance of a frost after this dateSpring, chance of a frost after the date: 10% April 27, 20% April 22, 30% April 19, 40% April 15, 50% April 12, 60% April 9, 70% April 5, 80% April 1, 90% March 28. Observed last spring frost in recent years: 2021 April 22, 2022 April 19, 2023 April 24, 2024 April 22, 2025 April 12, 2026 March 28.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 27Apr 12Mar 282021: April 222022: April 192023: April 242024: April 222025: April 122026: March 28Fall at St. Louis (Spirit of St. Louis Airport): chance of a frost before this dateFall, chance of a frost before the date: 10% October 11, 20% October 15, 30% October 19, 40% October 21, 50% October 23, 60% October 26, 70% October 29, 80% October 31, 90% November 5. Observed first fall frost in recent years: 2021 November 2, 2022 October 8, 2023 October 30, 2024 October 16, 2025 November 1.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 11Oct 23Nov 52021: November 22022: October 82023: October 302024: October 162025: November 1
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 2
2022April 19October 8
2023April 24October 30
2024April 22October 16
2025April 12November 1
2026March 28season not over yet

What these dates mean

October 11 marks the cautious fall date for finishing the harvest of tender crops in St. Louis at the Spirit of St. Louis Airport; there is only a 10 % chance that a light frost has arrived earlier.

For a spring planting strategy that minimizes risk, the cautious date is April 27, when the chance of a light frost later than that day is just 10 %. The 50 % date, April 12, signifies the median point where odds of frost are even, but it is not itself a frost date. Planting before March 28 would be a gamble, as that date carries a 90 % chance of a later frost.

Hard frosts at 28 °F are more damaging than light frosts at 32 °F, so the median hard-frost dates—March 31 in spring and November 3 in fall—are useful reference points for gardeners who must avoid temperatures that can kill tender tissue.

How to read the probabilities

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

  • Spring: "10% after April 27" 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 11" 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 St. Louis (Spirit of St. Louis Airport), MONumbered nearest stations: 1 — near Weldon Spring, MO — 3 mi; 2 — St. Charles, MO — 7 mi; 3 — Festus, MO — 32 mi; 4 — Jerseyville, IL — 35 mi; 5 — Elsberry, MO — 35 mi.MOIL25 mi · 40 km1. near Weldon Spring, MO — 3 mi12. St. Charles, MO — 7 mi23. Festus, MO — 32 mi34. Jerseyville, IL — 35 mi45. Elsberry, MO — 35 mi5
  1. near Weldon Spring, MO 3 mi (5 km)
  2. St. Charles, MO 7 mi (12 km)
  3. Festus, MO 32 mi (52 km)
  4. Jerseyville, IL 35 mi (56 km)
  5. Elsberry, MO 35 mi (57 km)

Sources

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

Station coordinates: 38.6572, -90.6558.