U.S. Frost Dates by Weather Station

NOAA station USC00112736 · Illinois

Frost Dates for Elgin, IL

NOAA weather station Elgin (USC00112736), Illinois · elevation 763 ft (233 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 12only 1 spring in 10 still has a frost later
  • Typical last frostApril 2650% chance of a frost after it
  • Typical first fall frostOctober 1850% chance of a frost before it
  • Frost-free season174 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Elgin, ILSpring: a frost after April 12 in 9 years out of 10, after April 26 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 3 in 1 year out of 10, before October 18 in half of the years, before October 31 in 9 years out of 10. Typical frost-free season: 174 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 26First frost ~Oct 18Frost season at Elgin, ILSpring: a frost after April 12 in 9 years out of 10, after April 26 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 3 in 1 year out of 10, before October 18 in half of the years, before October 31 in 9 years out of 10. Typical frost-free season: 174 days.JFMAMJJASONDLast frost ~Apr 26First frost ~Oct 18
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 12October 3
50% (typical)April 26October 18
90% (likely)April 12October 31
Frost-free season (32°F, 50% chance)
174 days
Hard frost (28°F), last in spring, 50% chance after
April 14
Hard frost (28°F), first in fall, 50% chance before
October 29

The last 15 years (2006–2020 normals)

Typical last frost April 26 (same as the 30-year normal), typical first fall frost October 21 (3 days later). Frost-free season 177 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 Elgin: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 12, 20% May 5, 30% May 1, 40% April 29, 50% April 26, 60% April 23, 70% April 20, 80% April 17, 90% April 12. Observed last spring frost in recent years: 2021 May 12, 2022 April 28, 2023 April 27, 2024 April 25, 2025 April 16, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 12Apr 26Apr 122021: May 122022: April 282023: April 272024: April 252025: April 162026: May 7Fall at Elgin: chance of a frost before this dateFall, chance of a frost before the date: 10% October 3, 20% October 8, 30% October 12, 40% October 15, 50% October 18, 60% October 20, 70% October 23, 80% October 26, 90% October 31. Observed first fall frost in recent years: 2021 November 2, 2022 October 8, 2023 October 30, 2024 October 17, 2025 October 24.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 3Oct 18Oct 312021: November 22022: October 82023: October 302024: October 172025: October 24
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
2021May 12November 2
2022April 28October 8
2023April 27October 30
2024April 25October 17
2025April 16October 24
2026May 7season not over yet

What these dates mean

May 12 is the cautious spring date for tender crops in Elgin, with only a 10 % chance that a light frost will appear later; after this day a gardener can plan to set out those crops with relatively low risk. The 50 % date of April 26 carries a 50 % chance of a light frost later than this date, while the early April 12 date carries a 90 % chance and is a gamble.

In the fall the cautious date is October 3, when there is just a 10 % chance that a light frost has already arrived, so a gardener can aim to finish harvesting tender crops by then. The 50 % date of October 18 carries a 50 % chance of a frost earlier than this date. Hard-frost thresholds of 28 °F occur on April 14 in spring and October 29 in fall; these lower temperatures can damage plants more severely than the 32 °F light frosts.

How to read the probabilities

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

  • Spring: "10% after May 12" 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 3" 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 Elgin, ILNumbered nearest stations: 1 — near McHenry, IL — 17 mi; 2 — Chicago (O'Hare Airport), IL — 19 mi; 3 — Aurora, IL — 20 mi; 4 — Chicago Botanic Garden, IL — 26 mi; 5 — De Kalb, IL — 27 mi.ILWIIN25 mi · 40 km1. near McHenry, IL — 17 mi12. Chicago (O'Hare Airport), IL — 19 mi23. Aurora, IL — 20 mi34. Chicago Botanic Garden, IL — 26 mi45. De Kalb, IL — 27 mi5
  1. near McHenry, IL 17 mi (28 km)
  2. Chicago (O'Hare Airport), IL 19 mi (30 km)
  3. Aurora, IL 20 mi (31 km)
  4. Chicago Botanic Garden, IL 26 mi (42 km)
  5. De Kalb, IL 27 mi (43 km)

Sources

* Hardiness zone 5b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 42.0628, -88.2861.