U.S. Frost Dates by Weather Station

NOAA station USC00117487 · Illinois

Frost Dates for Rosiclare, IL

NOAA weather station Rosiclare 5 NW (USC00117487), Illinois · elevation 400 ft (122 m) · hardiness zone 7a*

  • Lower-risk planting dateafter May 8only 1 spring in 10 still has a frost later
  • Typical last frostApril 1950% chance of a frost after it
  • Typical first fall frostOctober 2050% chance of a frost before it
  • Frost-free season181 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Rosiclare, ILSpring: a frost after April 3 in 9 years out of 10, after April 19 in half of the years, after May 8 in 1 year out of 10. Fall: the first frost comes before October 7 in 1 year out of 10, before October 20 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 181 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 19First frost ~Oct 20Frost season at Rosiclare, ILSpring: a frost after April 3 in 9 years out of 10, after April 19 in half of the years, after May 8 in 1 year out of 10. Fall: the first frost comes before October 7 in 1 year out of 10, before October 20 in half of the years, before October 30 in 9 years out of 10. Typical frost-free season: 181 days.JFMAMJJASONDLast frost ~Apr 19First frost ~Oct 20
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)May 8October 7
50% (typical)April 19October 20
90% (likely)April 3October 30
Frost-free season (32°F, 50% chance)
181 days
Hard frost (28°F), last in spring, 50% chance after
April 6
Hard frost (28°F), first in fall, 50% chance before
October 29

The last 15 years (2006–2020 normals)

Typical last frost April 21 (2 days later than the 30-year normal), typical first fall frost October 22 (2 days later). Frost-free season 183 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 Rosiclare: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 8, 20% May 2, 30% April 27, 40% April 23, 50% April 19, 60% April 16, 70% April 12, 80% April 8, 90% April 3. Observed last spring frost in recent years: 2021 April 22, 2022 April 20.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 8Apr 19Apr 32021: April 222022: April 20Fall at Rosiclare: chance of a frost before this dateFall, chance of a frost before the date: 10% October 7, 20% October 12, 30% October 15, 40% October 17, 50% October 20, 60% October 22, 70% October 24, 80% October 27, 90% October 30. Observed first fall frost in recent years: 2021 November 3, 2022 October 9.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 7Oct 20Oct 302021: November 32022: October 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 22November 3
2022April 20October 9
2023incomplete recordno data
2024no datano data
2025no datano data
2026no dataseason not over yet

What these dates mean

Setting out tender crops on the early spring date of April 3 is a gamble, because there is a 90 % chance of a frost later than that date. The cautious date for a low-risk planting is May 8, when only a 10 % chance of a frost remains.

The 50 % light-frost date of April 19 represents a 50 % chance of a frost later than this date, while the 50 % fall date of October 20 represents a 50 % chance of a frost earlier than this date; growers can use those benchmarks to gauge risk. The cautious fall date is October 7, carrying only a 10 % chance that a frost has arrived earlier.

The median hard-frost dates are April 6 in spring and October 29 in fall, and a hard frost at 28 °F can damage plants more severely than 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 May 8" 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 7" 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 Rosiclare, ILNumbered nearest stations: 1 — Smithland Lock and Dam, IL — 21 mi; 2 — near Metropolis, IL — 27 mi; 3 — Paducah, KY — 34 mi; 4 — Princeton, KY — 39 mi; 5 — Mount Vernon, IN — 42 mi.ILMOIN25 mi · 40 km1. Smithland Lock and Dam, IL — 21 mi12. near Metropolis, IL — 27 mi23. Paducah, KY — 34 mi34. Princeton, KY — 39 mi45. Mount Vernon, IN — 42 mi5
  1. Smithland Lock and Dam, IL 21 mi (35 km)
  2. near Metropolis, IL 27 mi (44 km)
  3. Paducah, KY 34 mi (55 km)
  4. Princeton, KY 39 mi (62 km)
  5. Mount Vernon, IN 42 mi (68 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: 37.4747, -88.4122.