U.S. Frost Dates by Weather Station

NOAA station USC00118293 · Illinois

Frost Dates for Stockton, IL

NOAA weather station Stockton 3 NNE (USC00118293), Illinois · elevation 970 ft (296 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 12only 1 spring in 10 still has a frost later
  • Typical last frostApril 2750% chance of a frost after it
  • Typical first fall frostOctober 950% chance of a frost before it
  • Frost-free season165 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Stockton, ILSpring: a frost after April 12 in 9 years out of 10, after April 27 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 9 in half of the years, before October 23 in 9 years out of 10. Typical frost-free season: 165 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 27First frost ~Oct 9Frost season at Stockton, ILSpring: a frost after April 12 in 9 years out of 10, after April 27 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before September 26 in 1 year out of 10, before October 9 in half of the years, before October 23 in 9 years out of 10. Typical frost-free season: 165 days.JFMAMJJASONDLast frost ~Apr 27First frost ~Oct 9
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 12September 26
50% (typical)April 27October 9
90% (likely)April 12October 23
Frost-free season (32°F, 50% chance)
165 days
Hard frost (28°F), last in spring, 50% chance after
April 17
Hard frost (28°F), first in fall, 50% chance before
October 21

The last 15 years (2006–2020 normals)

Typical last frost April 28 (1 day later than the 30-year normal), typical first fall frost October 13 (4 days later). Frost-free season 168 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 Stockton: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 12, 20% May 7, 30% May 3, 40% April 30, 50% April 27, 60% April 24, 70% April 21, 80% April 18, 90% April 12. Observed last spring frost in recent years: 2021 May 8, 2022 May 4, 2023 May 4, 2024 April 25, 2025 April 17, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 12Apr 27Apr 122021: May 82022: May 42023: May 42024: April 252025: April 172026: May 7Fall at Stockton: chance of a frost before this dateFall, chance of a frost before the date: 10% September 26, 20% September 30, 30% October 3, 40% October 6, 50% October 9, 60% October 12, 70% October 15, 80% October 18, 90% October 23. Observed first fall frost in recent years: 2021 October 23, 2022 September 29, 2023 October 11, 2024 October 15, 2025 October 23.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 26Oct 9Oct 232021: October 232022: September 292023: October 112024: October 152025: October 23
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 8October 23
2022May 4September 29
2023May 4October 11
2024April 25October 15
2025April 17October 23
2026May 7season not over yet

What these dates mean

Setting out tender crops on April 12 in Stockton carries a 90% chance that a light frost will still occur later that season, making it a gamble. The cautious date for planting tender crops is May 12, when the probability of a later frost drops to 10%.

For a gardener, the 50% spring date is April 27, which represents a fifty-fifty chance of a light frost later than this date, while the 50% fall date is October 9, indicating a fifty-fifty chance of a light frost earlier than this date. The cautious date for finishing tender crops in the fall is September 26, with only a ten-percent chance that a frost has arrived earlier.

Hard frosts at 28 °F are more damaging than 32 °F light frosts because they can kill plant tissue rather than merely chill it.

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 September 26" 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 Stockton, ILNumbered nearest stations: 1 — Freeport, IL — 21 mi; 2 — near Bellevue, IA — 24 mi; 3 — Brodhead, WI — 34 mi; 4 — Dubuque Lock and Dam 11, IA — 35 mi; 5 — Dubuque, IA — 36 mi.WIIA25 mi · 40 km1. Freeport, IL — 21 mi12. near Bellevue, IA — 24 mi23. Brodhead, WI — 34 mi34. Dubuque Lock and Dam 11, IA — 35 mi45. Dubuque, IA — 36 mi5
  1. Freeport, IL 21 mi (34 km)
  2. near Bellevue, IA 24 mi (39 km)
  3. Brodhead, WI 34 mi (55 km)
  4. Dubuque Lock and Dam 11, IA 35 mi (56 km)
  5. Dubuque, IA 36 mi (59 km)

Sources

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

Station coordinates: 42.3997, -89.9903.