U.S. Frost Dates by Weather Station

NOAA station USW00014835 · Indiana

Frost Dates for Lafayette (Purdue University Airport), IN

NOAA weather station Lafayette Purdue University Airport (USW00014835), Indiana · elevation 599 ft (183 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 14only 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 season173 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Lafayette (Purdue University Airport), INSpring: a frost after April 11 in 9 years out of 10, after April 26 in half of the years, after May 14 in 1 year out of 10. Fall: the first frost comes before October 4 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: 173 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 26First frost ~Oct 18Frost season at Lafayette (Purdue University Airport), INSpring: a frost after April 11 in 9 years out of 10, after April 26 in half of the years, after May 14 in 1 year out of 10. Fall: the first frost comes before October 4 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: 173 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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 14October 4
50% (typical)April 26October 18
90% (likely)April 11October 31
Frost-free season (32°F, 50% chance)
173 days
Hard frost (28°F), last in spring, 50% chance after
April 13
Hard frost (28°F), first in fall, 50% chance before
October 28

The last 15 years (2006–2020 normals)

Typical last frost April 26 (same as the 30-year normal), typical first fall frost October 20 (2 days later). Frost-free season 175 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 Lafayette (Purdue University Airport): chance of a frost after this dateSpring, chance of a frost after the date: 10% May 14, 20% May 7, 30% May 3, 40% April 30, 50% April 26, 60% April 23, 70% April 20, 80% April 16, 90% April 11. Observed last spring frost in recent years: 2021 April 2, 2022 April 27, 2023 April 26, 2024 April 25, 2025 April 16, 2026 April 20.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 14Apr 26Apr 112021: April 22022: April 272023: April 262024: April 252025: April 162026: April 20Fall at Lafayette (Purdue University Airport): chance of a frost before this dateFall, chance of a frost before the date: 10% October 4, 20% October 9, 30% October 13, 40% October 16, 50% October 18, 60% October 21, 70% October 23, 80% October 27, 90% October 31. Observed first fall frost in recent years: 2021 November 1, 2022 October 8, 2023 October 10, 2024 October 16, 2025 October 24.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 4Oct 18Oct 312021: November 12022: October 82023: October 102024: 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 2November 1
2022April 27October 8
2023April 26October 10
2024April 25October 16
2025April 16October 24
2026April 20season not over yet

What these dates mean

The 173 days between the 50% dates in Lafayette (April 26 to October 18) frame the period when light frosts are equally likely. The 50% date is April 26; there is a 50% chance of a frost later than this date. The 50% date is October 18; there is a 50% chance of a frost earlier than this date. Gardeners can use these median points to gauge the overall risk window across the 28-year record.

For a cautious plan, the spring light-frost date with a 10 % chance of frost later than the date is May 14, making it the advisable day to set out tender crops. In the fall, the cautious light-frost date with a 10 % chance of frost earlier than the date is October 4, the recommended day to finish harvesting tender crops. Hard frost at 28 °F can damage plants more severely than a light frost at 32 °F, and the 50% hard-frost dates are April 13 and October 28.

How to read the probabilities

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

  • Spring: "10% after May 14" 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 4" 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 Lafayette (Purdue University Airport), INNumbered nearest stations: 1 — West Lafayette, IN — 5 mi; 2 — Lafayette, IN — 8 mi; 3 — near Frankfort, IN — 24 mi; 4 — near Logansport, IN — 37 mi; 5 — Rensselaer, IN — 37 mi.IL25 mi · 40 km1. West Lafayette, IN — 5 mi12. Lafayette, IN — 8 mi23. near Frankfort, IN — 24 mi34. near Logansport, IN — 37 mi45. Rensselaer, IN — 37 mi5
  1. West Lafayette, IN 5 mi (8 km)
  2. Lafayette, IN 8 mi (13 km)
  3. near Frankfort, IN 24 mi (39 km)
  4. near Logansport, IN 37 mi (60 km)
  5. Rensselaer, IN 37 mi (60 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: 40.4122, -86.9369.