U.S. Frost Dates by Weather Station

NOAA station USC00238805 · Missouri

Frost Dates near Weldon Spring, MO

NOAA weather station Weldon Spring NWS (USC00238805), Missouri · elevation 610 ft (186 m) · hardiness zone 7a*

Weldon Spring is the nearest town to the station (1.1 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter April 26only 1 spring in 10 still has a frost later
  • Typical last frostApril 1050% chance of a frost after it
  • Typical first fall frostOctober 2650% chance of a frost before it
  • Frost-free season199 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season near Weldon Spring, MOSpring: a frost after March 26 in 9 years out of 10, after April 10 in half of the years, after April 26 in 1 year out of 10. Fall: the first frost comes before October 12 in 1 year out of 10, before October 26 in half of the years, before November 8 in 9 years out of 10. Typical frost-free season: 199 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 10First frost ~Oct 26Frost season near Weldon Spring, MOSpring: a frost after March 26 in 9 years out of 10, after April 10 in half of the years, after April 26 in 1 year out of 10. Fall: the first frost comes before October 12 in 1 year out of 10, before October 26 in half of the years, before November 8 in 9 years out of 10. Typical frost-free season: 199 days.JFMAMJJASONDLast frost ~Apr 10First frost ~Oct 26
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 26October 12
50% (typical)April 10October 26
90% (likely)March 26November 8
Frost-free season (32°F, 50% chance)
199 days
Hard frost (28°F), last in spring, 50% chance after
March 31
Hard frost (28°F), first in fall, 50% chance before
November 5

The last 15 years (2006–2020 normals)

Typical last frost April 8 (2 days earlier than the 30-year normal), typical first fall frost October 29 (3 days later). Frost-free season 201 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 near Weldon Spring: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 26, 20% April 20, 30% April 16, 40% April 13, 50% April 10, 60% April 7, 70% April 4, 80% March 31, 90% March 26. Observed last spring frost in recent years: 2021 April 23, 2022 April 20, 2023 April 25, 2024 March 29, 2026 March 29.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 26Apr 10Mar 262021: April 232022: April 202023: April 252024: March 292026: March 29Fall near Weldon Spring: chance of a frost before this dateFall, chance of a frost before the date: 10% October 12, 20% October 17, 30% October 20, 40% October 23, 50% October 26, 60% October 29, 70% October 31, 80% November 2, 90% November 8. Observed first fall frost in recent years: 2021 November 3, 2022 October 18, 2023 October 31, 2024 November 24, 2025 November 10.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Dec 1Oct 12Oct 26Nov 82021: November 32022: October 182023: October 312024: November 242025: November 10
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 3
2022April 20October 18
2023April 25October 31
2024March 29November 24
2025incomplete recordNovember 10
2026March 29season not over yet

What these dates mean

Setting out tender crops on the early spring date of March 26 carries a 90 % chance of a frost later that season, so planting then is a gamble for the Weldon Spring area.

The 50 % date is April 10, meaning there is an even odds (50 % chance) of a frost later than this date. In the fall, the 50 % date is October 26, with a 50 % chance of a frost earlier than it. A cautious plan would wait until the April 26 date, which has only a 10 % chance of a frost later, and would finish harvesting tender crops by October 12, when there is only a 10 % chance that a frost has arrived earlier.

Hard frosts at 28 °F are more damaging than light frosts at 32 °F, and the median hard-frost dates are March 31 in spring and November 5 in fall.

How to read the probabilities

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

  • Spring: "10% after April 26" 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 12" 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 Weldon Spring, MONumbered nearest stations: 1 — St. Louis (Spirit of St. Louis Airport), MO — 3 mi; 2 — St. Charles, MO — 9 mi; 3 — Elsberry, MO — 32 mi; 4 — Jerseyville, IL — 33 mi; 5 — Festus, MO — 36 mi.MOIL25 mi · 40 km1. St. Louis (Spirit of St. Louis Airport), MO — 3 mi12. St. Charles, MO — 9 mi23. Elsberry, MO — 32 mi34. Jerseyville, IL — 33 mi45. Festus, MO — 36 mi5
  1. St. Louis (Spirit of St. Louis Airport), MO 3 mi (5 km)
  2. St. Charles, MO 9 mi (14 km)
  3. Elsberry, MO 32 mi (52 km)
  4. Jerseyville, IL 33 mi (54 km)
  5. Festus, MO 36 mi (57 km)

Sources

* Hardiness zone 7a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 38.6989, -90.6828.