U.S. Frost Dates by Weather Station

NOAA station USC00111290 · Illinois

Frost Dates near Carlyle, IL

NOAA weather station Carlyle Reservoir (USC00111290), Illinois · elevation 501 ft (153 m) · hardiness zone 6b*

Carlyle 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 22only 1 spring in 10 still has a frost later
  • Typical last frostApril 650% chance of a frost after it
  • Typical first fall frostOctober 2950% chance of a frost before it
  • Frost-free season204 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season near Carlyle, ILSpring: a frost after March 23 in 9 years out of 10, after April 6 in half of the years, after April 22 in 1 year out of 10. Fall: the first frost comes before October 16 in 1 year out of 10, before October 29 in half of the years, before November 12 in 9 years out of 10. Typical frost-free season: 204 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 6First frost ~Oct 29Frost season near Carlyle, ILSpring: a frost after March 23 in 9 years out of 10, after April 6 in half of the years, after April 22 in 1 year out of 10. Fall: the first frost comes before October 16 in 1 year out of 10, before October 29 in half of the years, before November 12 in 9 years out of 10. Typical frost-free season: 204 days.JFMAMJJASONDLast frost ~Apr 6First frost ~Oct 29
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 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 22October 16
50% (typical)April 6October 29
90% (likely)March 23November 12
Frost-free season (32°F, 50% chance)
204 days
Hard frost (28°F), last in spring, 50% chance after
March 28
Hard frost (28°F), first in fall, 50% chance before
November 8

The last 15 years (2006–2020 normals)

Typical last frost April 7 (1 day later than the 30-year normal), typical first fall frost October 30 (1 day later). Frost-free season 206 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 Carlyle: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 22, 20% April 17, 30% April 13, 40% April 9, 50% April 6, 60% April 4, 70% April 1, 80% March 29, 90% March 23. Observed last spring frost in recent years: 2021 April 22, 2023 March 21, 2024 March 20, 2025 April 9, 2026 March 29.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 22Apr 6Mar 232021: April 222023: March 212024: March 202025: April 92026: March 29Fall near Carlyle: chance of a frost before this dateFall, chance of a frost before the date: 10% October 16, 20% October 21, 30% October 24, 40% October 27, 50% October 29, 60% October 31, 70% November 3, 80% November 6, 90% November 12. Observed first fall frost in recent years: 2022 October 18, 2023 October 31, 2024 November 26, 2025 November 9.Fall: first frostChance of a frost before this date10%50%90%Nov 1Dec 1Oct 16Oct 29Nov 122022: October 182023: October 312024: November 262025: 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 22incomplete record
2022incomplete recordOctober 18
2023March 21October 31
2024March 20November 26
2025April 9November 9
2026March 29season not over yet

What these dates mean

Planting tender crops on March 23 in the Carlyle area is a gamble, because there is a 90% chance that a light frost will still occur later that spring. The cautious date for a light-frost risk in spring is April 22, when only a 10% chance of a later frost remains; in fall the cautious date to finish tender crops is October 16, with a 10% chance that a frost has already arrived.

The 50% date is April 6, meaning there is an even-odds chance of a frost later than that day, and the 50% date is October 29, meaning an even-odds chance of a frost earlier than that day. A hard frost at 28 °F, marked by the 50% dates March 28 and November 8, can injure plants that would survive a light frost at 32 °F.

How to read the probabilities

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

  • Spring: "10% after April 22" 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 16" 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 Carlyle, ILNumbered nearest stations: 1 — Nashville, IL — 20 mi; 2 — Salem, IL — 23 mi; 3 — near Belleville, IL — 27 mi; 4 — Mount Vernon, IL — 34 mi; 5 — Hillsboro, IL — 38 mi.ILMOIN25 mi · 40 km1. Nashville, IL — 20 mi12. Salem, IL — 23 mi23. near Belleville, IL — 27 mi34. Mount Vernon, IL — 34 mi45. Hillsboro, IL — 38 mi5
  1. Nashville, IL 20 mi (31 km)
  2. Salem, IL 23 mi (36 km)
  3. near Belleville, IL 27 mi (44 km)
  4. Mount Vernon, IL 34 mi (54 km)
  5. Hillsboro, IL 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: 38.625, -89.3631.