U.S. Frost Dates by Weather Station

NOAA station USC00116446 · Illinois

Frost Dates for Olney, IL

NOAA weather station Olney 2 S (USC00116446), Illinois · elevation 459 ft (140 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 3only 1 spring in 10 still has a frost later
  • Typical last frostApril 1550% chance of a frost after it
  • Typical first fall frostOctober 2350% chance of a frost before it
  • Frost-free season189 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Olney, ILSpring: a frost after April 1 in 9 years out of 10, after April 15 in half of the years, after May 3 in 1 year out of 10. Fall: the first frost comes before October 8 in 1 year out of 10, before October 23 in half of the years, before November 3 in 9 years out of 10. Typical frost-free season: 189 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 15First frost ~Oct 23Frost season at Olney, ILSpring: a frost after April 1 in 9 years out of 10, after April 15 in half of the years, after May 3 in 1 year out of 10. Fall: the first frost comes before October 8 in 1 year out of 10, before October 23 in half of the years, before November 3 in 9 years out of 10. Typical frost-free season: 189 days.JFMAMJJASONDLast frost ~Apr 15First 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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 3October 8
50% (typical)April 15October 23
90% (likely)April 1November 3
Frost-free season (32°F, 50% chance)
189 days
Hard frost (28°F), last in spring, 50% chance after
April 3
Hard frost (28°F), first in fall, 50% chance before
November 1

The last 15 years (2006–2020 normals)

Typical last frost April 13 (2 days earlier than the 30-year normal), typical first fall frost October 26 (3 days later). Frost-free season 194 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 Olney: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 3, 20% April 26, 30% April 22, 40% April 18, 50% April 15, 60% April 11, 70% April 8, 80% April 5, 90% April 1. Observed last spring frost in recent years: 2021 April 22, 2022 April 20, 2023 April 25, 2024 April 7, 2025 April 9.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 3Apr 15Apr 12021: April 222022: April 202023: April 252024: April 72025: April 9Fall at Olney: chance of a frost before this dateFall, chance of a frost before the date: 10% October 8, 20% October 13, 30% October 17, 40% October 20, 50% October 23, 60% October 25, 70% October 28, 80% October 31, 90% November 3. Observed first fall frost in recent years: 2021 November 3, 2022 October 9, 2023 October 31, 2024 October 16, 2025 November 2.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 8Oct 23Nov 32021: November 32022: October 92023: October 312024: October 162025: November 2
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 3
2022April 20October 9
2023April 25October 31
2024April 7October 16
2025April 9November 2
2026incomplete recordseason not over yet

What these dates mean

May 3 is the cautious spring date for tender crops in Olney; only a 10 % chance of a light frost later lets a gardener schedule planting with low risk. The median light-frost date, April 15, marks the point where a frost is equally likely to occur, while the 50 % hard-frost date, April 3, indicates an even chance of a 28 °F event. In the fall, October 8 serves as the cautious date to finish harvesting tender crops, because there is only a 10 % chance a light frost has already arrived. The median light-frost date, October 23, represents even odds for a frost, and the 50 % hard-frost date, November 1, shows an equal chance of a 28 °F freeze. A hard frost matters more than a light frost because temperatures of 28 °F can damage or kill plants that would survive a 32 °F chill.

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 8" 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 Olney, ILNumbered nearest stations: 1 — near Fairfield, IL — 26 mi; 2 — Vincennes, IN — 32 mi; 3 — Princeton, IN — 36 mi; 4 — Effingham, IL — 41 mi; 5 — Carmi, IL — 44 mi.ILINKY25 mi · 40 km1. near Fairfield, IL — 26 mi12. Vincennes, IN — 32 mi23. Princeton, IN — 36 mi34. Effingham, IL — 41 mi45. Carmi, IL — 44 mi5
  1. near Fairfield, IL 26 mi (41 km)
  2. Vincennes, IN 32 mi (52 km)
  3. Princeton, IN 36 mi (57 km)
  4. Effingham, IL 41 mi (66 km)
  5. Carmi, IL 44 mi (70 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: 38.7003, -88.0817.