U.S. Frost Dates by Weather Station

NOAA station USC00114442 · Illinois

Frost Dates for Jacksonville, IL

NOAA weather station Jacksonville 2 E (USC00114442), Illinois · elevation 610 ft (186 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 5only 1 spring in 10 still has a frost later
  • Typical last frostApril 1950% chance of a frost after it
  • Typical first fall frostOctober 1750% chance of a frost before it
  • Frost-free season179 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Jacksonville, ILSpring: a frost after April 5 in 9 years out of 10, after April 19 in half of the years, after May 5 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 17 in half of the years, before October 29 in 9 years out of 10. Typical frost-free season: 179 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 19First frost ~Oct 17Frost season at Jacksonville, ILSpring: a frost after April 5 in 9 years out of 10, after April 19 in half of the years, after May 5 in 1 year out of 10. Fall: the first frost comes before October 1 in 1 year out of 10, before October 17 in half of the years, before October 29 in 9 years out of 10. Typical frost-free season: 179 days.JFMAMJJASONDLast frost ~Apr 19First frost ~Oct 17
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 5October 1
50% (typical)April 19October 17
90% (likely)April 5October 29
Frost-free season (32°F, 50% chance)
179 days
Hard frost (28°F), last in spring, 50% chance after
April 7
Hard frost (28°F), first in fall, 50% chance before
October 27

The last 15 years (2006–2020 normals)

Typical last frost April 20 (1 day later than the 30-year normal), typical first fall frost October 20 (3 days later). Frost-free season 182 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 Jacksonville: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 5, 20% April 30, 30% April 26, 40% April 22, 50% April 19, 60% April 16, 70% April 12, 80% April 9, 90% April 5. Observed last spring frost in recent years: 2021 April 23, 2022 April 20, 2023 April 25, 2024 April 7, 2025 April 9, 2026 April 21.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 5Apr 19Apr 52021: April 232022: April 202023: April 252024: April 72025: April 92026: April 21Fall at Jacksonville: chance of a frost before this dateFall, chance of a frost before the date: 10% October 1, 20% October 7, 30% October 11, 40% October 15, 50% October 17, 60% October 20, 70% October 22, 80% October 26, 90% October 29. Observed first fall frost in recent years: 2021 November 2, 2022 October 8, 2023 October 30, 2024 October 16, 2025 October 24.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 1Oct 17Oct 292021: November 22022: October 82023: October 302024: October 162025: 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
2021April 23November 2
2022April 20October 8
2023April 25October 30
2024April 7October 16
2025April 9October 24
2026April 21season not over yet

What these dates mean

May 5 is the cautious spring date for light frost in Jacksonville; with only a 10 % chance of a frost later, a gardener can plan to set out tender crops after this point. The median light-frost date in spring is April 19, an even-odds point for a frost occurring later, while April 5 carries a 90 % chance of frost and is a gamble. In the fall the cautious date is October 1, when there is only a 10 % chance that a frost has arrived earlier, allowing a gardener to finish harvesting tender crops with minimal risk.

The median light-frost date for autumn is October 17, representing an even chance of frost having arrived earlier, and October 29 carries a 90 % gamble of frost already being present. Hard frost (28 °F) is noted by the 50 % dates of April 7 in spring and October 27 in fall; these dates matter because a hard frost can damage or kill plants that survive a light frost.

How to read the probabilities

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

  • Spring: "10% after May 5" 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 1" 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 Jacksonville, ILNumbered nearest stations: 1 — White Hall, IL — 22 mi; 2 — near Springfield, IL — 28 mi; 3 — Jerseyville, IL — 44 mi; 4 — Elsberry, MO — 51 mi; 5 — Lincoln, IL — 54 mi.ILMO25 mi · 40 km1. White Hall, IL — 22 mi12. near Springfield, IL — 28 mi23. Jerseyville, IL — 44 mi34. Elsberry, MO — 51 mi45. Lincoln, IL — 54 mi5
  1. White Hall, IL 22 mi (36 km)
  2. near Springfield, IL 28 mi (46 km)
  3. Jerseyville, IL 44 mi (71 km)
  4. Elsberry, MO 51 mi (82 km)
  5. Lincoln, IL 54 mi (87 km)

Sources

* Hardiness zone 6a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 39.7347, -90.1978.