U.S. Frost Dates by Weather Station

NOAA station USC00237578 · Missouri

Frost Dates for Saverton Lock and Dam 22, MO

NOAA weather station Saverton Lock and Dam 22 (USC00237578), Missouri · elevation 472 ft (144 m) · hardiness zone 6b*

  • Lower-risk planting dateafter April 19only 1 spring in 10 still has a frost later
  • Typical last frostApril 450% chance of a frost after it
  • Typical first fall frostNovember 450% chance of a frost before it
  • Frost-free season212 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Saverton Lock and Dam 22, MOSpring: a frost after March 20 in 9 years out of 10, after April 4 in half of the years, after April 19 in 1 year out of 10. Fall: the first frost comes before October 23 in 1 year out of 10, before November 4 in half of the years, before November 18 in 9 years out of 10. Typical frost-free season: 212 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 4First frost ~Nov 4Frost season at Saverton Lock and Dam 22, MOSpring: a frost after March 20 in 9 years out of 10, after April 4 in half of the years, after April 19 in 1 year out of 10. Fall: the first frost comes before October 23 in 1 year out of 10, before November 4 in half of the years, before November 18 in 9 years out of 10. Typical frost-free season: 212 days.JFMAMJJASONDLast frost ~Apr 4First frost ~Nov 4
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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 19October 23
50% (typical)April 4November 4
90% (likely)March 20November 18
Frost-free season (32°F, 50% chance)
212 days
Hard frost (28°F), last in spring, 50% chance after
March 26
Hard frost (28°F), first in fall, 50% chance before
November 14

The last 15 years (2006–2020 normals)

Typical last frost April 4 (same as the 30-year normal), typical first fall frost November 2 (2 days earlier). Frost-free season 213 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 Saverton Lock and Dam 22: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 19, 20% April 13, 30% April 9, 40% April 7, 50% April 4, 60% April 2, 70% March 31, 80% March 25, 90% March 20. Observed last spring frost in recent years: 2021 April 23, 2022 April 2, 2023 March 21, 2024 March 28, 2025 April 9, 2026 March 29.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 19Apr 4Mar 202021: April 232022: April 22023: March 212024: March 282025: April 92026: March 29Fall at Saverton Lock and Dam 22: chance of a frost before this dateFall, chance of a frost before the date: 10% October 23, 20% October 28, 30% October 31, 40% November 1, 50% November 4, 60% November 6, 70% November 9, 80% November 13, 90% November 18. Observed first fall frost in recent years: 2022 October 20, 2023 October 30, 2024 November 23, 2025 November 3.Fall: first frostChance of a frost before this date10%50%90%Nov 1Dec 1Oct 23Nov 4Nov 182022: October 202023: October 302024: November 232025: November 3
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 23incomplete record
2022April 2October 20
2023March 21October 30
2024March 28November 23
2025April 9November 3
2026March 29season not over yet

What these dates mean

April 19 is the cautious spring date for setting out tender crops at Saverton Lock and Dam 22; only a 10 % chance of a light frost later than that day means a gardener can plan to plant sensitive seedlings with relatively low risk. In the fall the cautious date is October 23, when there is only a 10 % chance that a light frost has already arrived, allowing the gardener to finish harvesting tender crops before frost becomes likely.

April 4 is the 50 % median date for light frost in spring, indicating an even chance that a 32 °F frost could occur later, while November 4 serves the same role for fall, marking an even chance that a 32 °F frost could have happened earlier. The hard-frost 50 % dates are March 26 in spring and November 14 in fall; a hard frost reaches 28 °F, a temperature low enough to damage plant tissue that survives only a light frost. These reference points help the gardener gauge timing for planting and harvesting.

How to read the probabilities

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

  • Spring: "10% after April 19" 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 23" 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 Saverton Lock and Dam 22, MONumbered nearest stations: 1 — Hannibal, MO — 9 mi; 2 — Quincy Dam 21, IL — 21 mi; 3 — Quincy, IL — 21 mi; 4 — Vandalia, MO — 26 mi; 5 — near Canton, MO — 38 mi.MOIL25 mi · 40 km1. Hannibal, MO — 9 mi12. Quincy Dam 21, IL — 21 mi23. Quincy, IL — 21 mi34. Vandalia, MO — 26 mi45. near Canton, MO — 38 mi5
  1. Hannibal, MO 9 mi (14 km)
  2. Quincy Dam 21, IL 21 mi (33 km)
  3. Quincy, IL 21 mi (34 km)
  4. Vandalia, MO 26 mi (42 km)
  5. near Canton, MO 38 mi (61 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: 39.6361, -91.25.