U.S. Frost Dates by Weather Station

NOAA station USC00114489 · Illinois

Frost Dates for Jerseyville, IL

NOAA weather station Jerseyville 2 SW (USC00114489), Illinois · elevation 630 ft (192 m) · hardiness zone 6b*

  • Lower-risk planting dateafter April 30only 1 spring in 10 still has a frost later
  • Typical last frostApril 1450% chance of a frost after it
  • Typical first fall frostOctober 1950% chance of a frost before it
  • Frost-free season187 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Jerseyville, ILSpring: a frost after March 31 in 9 years out of 10, after April 14 in half of the years, after April 30 in 1 year out of 10. Fall: the first frost comes before October 7 in 1 year out of 10, before October 19 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 187 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 14First frost ~Oct 19Frost season at Jerseyville, ILSpring: a frost after March 31 in 9 years out of 10, after April 14 in half of the years, after April 30 in 1 year out of 10. Fall: the first frost comes before October 7 in 1 year out of 10, before October 19 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 187 days.JFMAMJJASONDLast frost ~Apr 14First frost ~Oct 19
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 25 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 30October 7
50% (typical)April 14October 19
90% (likely)March 31November 1
Frost-free season (32°F, 50% chance)
187 days
Hard frost (28°F), last in spring, 50% chance after
April 4
Hard frost (28°F), first in fall, 50% chance before
October 30

The last 15 years (2006–2020 normals)

Typical last frost April 14 (same as the 30-year normal), typical first fall frost October 22 (3 days later). Frost-free season 188 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 Jerseyville: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 30, 20% April 25, 30% April 21, 40% April 17, 50% April 14, 60% April 11, 70% April 8, 80% April 5, 90% March 31. Observed last spring frost in recent years: 2021 April 23, 2022 April 20, 2023 April 24, 2024 April 20, 2025 April 9, 2026 March 28.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 30Apr 14Mar 312021: April 232022: April 202023: April 242024: April 202025: April 92026: March 28Fall at Jerseyville: chance of a frost before this dateFall, chance of a frost before the date: 10% October 7, 20% October 12, 30% October 15, 40% October 17, 50% October 19, 60% October 22, 70% October 25, 80% October 28, 90% November 1. 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 7Oct 19Nov 12021: 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 24October 30
2024April 20October 16
2025April 9October 24
2026March 28season not over yet

What these dates mean

The cautious fall date in Jerseyville for finishing the harvest is October 7, when there is only a 10 % chance that a light frost has arrived.

For a gardener, the 50 % light-frost dates are April 14 and October 19; each marks an even-odds point, with a 50 % chance of a frost later than April 14 in spring and a 50 % chance of a frost earlier than October 19 in fall. A cautious plan therefore uses April 30 as the spring date to set out tender crops and October 7 as the fall date to finish harvesting them. The 50 % hard-frost dates are April 4 and October 30, and a hard frost at 28 °F can damage plants more severely than a light frost at 32 °F.

The two 32°F 50% dates are April 14 and October 19, producing a frost-free interval of 187 days based on 25 years of record.

How to read the probabilities

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

  • Spring: "10% after April 30" 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 7" 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 Jerseyville, ILNumbered nearest stations: 1 — White Hall, IL — 23 mi; 2 — Elsberry, MO — 24 mi; 3 — St. Charles, MO — 30 mi; 4 — near Weldon Spring, MO — 33 mi; 5 — St. Louis (Spirit of St. Louis Airport), MO — 35 mi.ILMO25 mi · 40 km1. White Hall, IL — 23 mi12. Elsberry, MO — 24 mi23. St. Charles, MO — 30 mi34. near Weldon Spring, MO — 33 mi45. St. Louis (Spirit of St. Louis Airport), MO — 35 mi5
  1. White Hall, IL 23 mi (38 km)
  2. Elsberry, MO 24 mi (38 km)
  3. St. Charles, MO 30 mi (49 km)
  4. near Weldon Spring, MO 33 mi (54 km)
  5. St. Louis (Spirit of St. Louis Airport), MO 35 mi (56 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: 39.1025, -90.3431.