U.S. Frost Dates by Weather Station

NOAA station USC00110993 · Illinois

Frost Dates near Metropolis, IL

NOAA weather station Brookport Dam 52 (USC00110993), Illinois · elevation 330 ft (101 m) · hardiness zone 7a*

Metropolis is the nearest town to the station (4.7 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 23only 1 spring in 10 still has a frost later
  • Typical last frostApril 650% chance of a frost after it
  • Typical first fall frostOctober 2750% chance of a frost before it
  • Frost-free season203 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season near Metropolis, ILSpring: a frost after March 21 in 9 years out of 10, after April 6 in half of the years, after April 23 in 1 year out of 10. Fall: the first frost comes before October 15 in 1 year out of 10, before October 27 in half of the years, before November 9 in 9 years out of 10. Typical frost-free season: 203 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 6First frost ~Oct 27Frost season near Metropolis, ILSpring: a frost after March 21 in 9 years out of 10, after April 6 in half of the years, after April 23 in 1 year out of 10. Fall: the first frost comes before October 15 in 1 year out of 10, before October 27 in half of the years, before November 9 in 9 years out of 10. Typical frost-free season: 203 days.JFMAMJJASONDLast frost ~Apr 6First frost ~Oct 27
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 23October 15
50% (typical)April 6October 27
90% (likely)March 21November 9
Frost-free season (32°F, 50% chance)
203 days
Hard frost (28°F), last in spring, 50% chance after
March 27
Hard frost (28°F), first in fall, 50% chance before
November 5

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 29 (2 days later). Frost-free season 203 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 Metropolis: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 23, 20% April 17, 30% April 12, 40% April 9, 50% April 6, 60% April 3, 70% March 31, 80% March 28, 90% March 21.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 23Apr 6Mar 21Fall near Metropolis: chance of a frost before this dateFall, chance of a frost before the date: 10% October 15, 20% October 20, 30% October 23, 40% October 25, 50% October 27, 60% October 30, 70% November 1, 80% November 4, 90% November 9.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 15Oct 27Nov 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.

What these dates mean

Setting out tender crops on March 21 in the Metropolis area carries a 90% chance of a frost, so it is a gamble for gardeners. The cautious spring date is April 23, when there is only a 10% chance of a frost later than that day. The median 32 °F date, April 6, represents a 50% chance of a frost later than this date, giving a reference point for risk.

In fall, the cautious date to finish harvesting tender crops is October 15, with a 10% chance of a frost earlier than that day, while November 9 is a gamble because a frost earlier is 90% likely. October 27 is the median 32 °F date, marking a 50% chance of a frost earlier than this date. The hard-frost median dates are March 27 in spring and November 5 in fall; 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 April 23" 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 15" 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 Metropolis, ILNumbered nearest stations: 1 — Paducah, KY — 8 mi; 2 — Smithland Lock and Dam, IL — 12 mi; 3 — Rosiclare, IL — 27 mi; 4 — Murray, KY — 40 mi; 5 — Princeton, KY — 43 mi.TNILMO25 mi · 40 km1. Paducah, KY — 8 mi12. Smithland Lock and Dam, IL — 12 mi23. Rosiclare, IL — 27 mi34. Murray, KY — 40 mi45. Princeton, KY — 43 mi5
  1. Paducah, KY 8 mi (12 km)
  2. Smithland Lock and Dam, IL 12 mi (20 km)
  3. Rosiclare, IL 27 mi (44 km)
  4. Murray, KY 40 mi (65 km)
  5. Princeton, KY 43 mi (70 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: 37.1275, -88.6531.