U.S. Frost Dates by Weather Station

NOAA station USC00117636 · Illinois

Frost Dates for Salem, IL

NOAA weather station Salem (USC00117636), Illinois · elevation 550 ft (168 m) · hardiness zone 6b*

  • Lower-risk planting dateafter April 23only 1 spring in 10 still has a frost later
  • Typical last frostApril 950% chance of a frost after it
  • Typical first fall frostOctober 2650% chance of a frost before it
  • Frost-free season197 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Salem, ILSpring: a frost after March 25 in 9 years out of 10, after April 9 in half of the years, after April 23 in 1 year out of 10. Fall: the first frost comes before October 13 in 1 year out of 10, before October 26 in half of the years, before November 6 in 9 years out of 10. Typical frost-free season: 197 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 9First frost ~Oct 26Frost season at Salem, ILSpring: a frost after March 25 in 9 years out of 10, after April 9 in half of the years, after April 23 in 1 year out of 10. Fall: the first frost comes before October 13 in 1 year out of 10, before October 26 in half of the years, before November 6 in 9 years out of 10. Typical frost-free season: 197 days.JFMAMJJASONDLast frost ~Apr 9First frost ~Oct 26
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 23October 13
50% (typical)April 9October 26
90% (likely)March 25November 6
Frost-free season (32°F, 50% chance)
197 days
Hard frost (28°F), last in spring, 50% chance after
March 30
Hard frost (28°F), first in fall, 50% chance before
November 3

The last 15 years (2006–2020 normals)

Typical last frost April 8 (1 day earlier than the 30-year normal), typical first fall frost October 29 (3 days later). Frost-free season 202 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 Salem: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 23, 20% April 18, 30% April 14, 40% April 11, 50% April 9, 60% April 5, 70% April 3, 80% March 31, 90% March 25. Observed last spring frost in recent years: 2021 April 22, 2022 April 20, 2023 April 25, 2024 March 29, 2025 April 9, 2026 March 19.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 23Apr 9Mar 252021: April 222022: April 202023: April 252024: March 292025: April 92026: March 19Fall at Salem: chance of a frost before this dateFall, chance of a frost before the date: 10% October 13, 20% October 18, 30% October 21, 40% October 24, 50% October 26, 60% October 29, 70% October 31, 80% November 2, 90% November 6. Observed first fall frost in recent years: 2022 October 18, 2023 October 31, 2024 November 26, 2025 November 10.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Dec 1Oct 13Oct 26Nov 62022: October 182023: October 312024: November 262025: November 10
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
2022April 20October 18
2023April 25October 31
2024March 29November 26
2025April 9November 10
2026March 19season not over yet

What these dates mean

The 197 days between the 32°F 50% dates of April 9 and October 26 frame the period when a light frost is no more likely than not for Salem gardeners. Within this window the risk of a 32°F frost drops below 50 % after April 9 and stays below 50 % until October 26, so planting can proceed with moderate confidence.

For a cautious spring plan the 10 % chance date of April 23 is used to set out tender crops, while a cautious fall plan uses the 10 % chance date of October 13 to finish harvesting those crops. A hard frost, defined at 28°F, is more damaging than a light frost because it can injure plant tissue that survives a 32°F chill. The median hard-frost dates are March 30 in spring and November 3 in fall, marking when a 50 % chance of a deeper freeze exists.

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 13" 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 Salem, ILNumbered nearest stations: 1 — Mount Vernon, IL — 21 mi; 2 — near Carlyle, IL — 23 mi; 3 — Nashville, IL — 30 mi; 4 — Ramsey, IL — 36 mi; 5 — Effingham, IL — 37 mi.ILINMO25 mi · 40 km1. Mount Vernon, IL — 21 mi12. near Carlyle, IL — 23 mi23. Nashville, IL — 30 mi34. Ramsey, IL — 36 mi45. Effingham, IL — 37 mi5
  1. Mount Vernon, IL 21 mi (33 km)
  2. near Carlyle, IL 23 mi (36 km)
  3. Nashville, IL 30 mi (49 km)
  4. Ramsey, IL 36 mi (58 km)
  5. Effingham, IL 37 mi (60 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: 38.6403, -88.9458.