U.S. Frost Dates by Weather Station

NOAA station USC00126001 · Indiana

Frost Dates for Mount Vernon, IN

NOAA weather station Mount Vernon (USC00126001), Indiana · elevation 357 ft (109 m) · hardiness zone 7a*

  • Lower-risk planting dateafter April 27only 1 spring in 10 still has a frost later
  • Typical last frostApril 750% chance of a frost after it
  • Typical first fall frostOctober 2850% chance of a frost before it
  • Frost-free season202 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Mount Vernon, INSpring: a frost after March 25 in 9 years out of 10, after April 7 in half of the years, after April 27 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 28 in half of the years, before November 10 in 9 years out of 10. Typical frost-free season: 202 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 7First frost ~Oct 28Frost season at Mount Vernon, INSpring: a frost after March 25 in 9 years out of 10, after April 7 in half of the years, after April 27 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 28 in half of the years, before November 10 in 9 years out of 10. Typical frost-free season: 202 days.JFMAMJJASONDLast frost ~Apr 7First frost ~Oct 28
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 27October 10
50% (typical)April 7October 28
90% (likely)March 25November 10
Frost-free season (32°F, 50% chance)
202 days
Hard frost (28°F), last in spring, 50% chance after
March 30
Hard frost (28°F), first in fall, 50% chance before
November 7

The last 15 years (2006–2020 normals)

Typical last frost April 6 (1 day earlier than the 30-year normal), typical first fall frost October 30 (2 days later). Frost-free season 206 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 Mount Vernon: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 27, 20% April 20, 30% April 15, 40% April 11, 50% April 7, 60% April 5, 70% April 2, 80% March 31, 90% March 25. Observed last spring frost in recent years: 2021 April 22, 2023 March 21, 2024 March 20, 2025 April 9.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 27Apr 7Mar 252021: April 222023: March 212024: March 202025: April 9Fall at Mount Vernon: chance of a frost before this dateFall, chance of a frost before the date: 10% October 10, 20% October 16, 30% October 21, 40% October 25, 50% October 28, 60% October 30, 70% November 1, 80% November 5, 90% November 10. Observed first fall frost in recent years: 2021 November 3, 2024 November 26.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Dec 1Oct 10Oct 28Nov 102021: November 32024: November 26
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 22November 3
2022no dataincomplete record
2023March 21incomplete record
2024March 20November 26
2025April 9incomplete record
2026incomplete recordseason not over yet

What these dates mean

April 27 is the cautious spring date for Mount Vernon, allowing a gardener to set out tender crops with only a 10 % chance of a later light frost. The 50% light-frost date in spring is April 7, which marks an even-odds point for frost occurrence, while the median hard-frost date is March 30. Based on 26 years of NOAA data, the two 32°F 50% dates—April 7 and October 28—frame a frost-free interval of 202 days.

In fall, October 10 serves as the cautious date to finish harvesting tender crops, carrying a 10 % chance that a light frost has arrived earlier. The 50% light-frost date for fall is October 28 and the median hard-frost date is November 7. A hard frost at 28 °F can damage plants that survive a light frost at 32 °F, making it a more critical threshold for garden planning.

How to read the probabilities

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

  • Spring: "10% after April 27" 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 10" 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 Mount Vernon, INNumbered nearest stations: 1 — Henderson, KY — 18 mi; 2 — Carmi, IL — 18 mi; 3 — Evansville, IN — 22 mi; 4 — Princeton, IN — 34 mi; 5 — Boonville, IN — 35 mi.ILINKY25 mi · 40 km1. Henderson, KY — 18 mi12. Carmi, IL — 18 mi23. Evansville, IN — 22 mi34. Princeton, IN — 34 mi45. Boonville, IN — 35 mi5
  1. Henderson, KY 18 mi (29 km)
  2. Carmi, IL 18 mi (30 km)
  3. Evansville, IN 22 mi (35 km)
  4. Princeton, IN 34 mi (55 km)
  5. Boonville, IN 35 mi (56 km)

Sources

* Hardiness zone 7a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 37.9286, -87.8956.