U.S. Frost Dates by Weather Station

NOAA station USC00127125 · Indiana

Frost Dates for Princeton, IN

NOAA weather station Princeton 1 W (USC00127125), Indiana · elevation 480 ft (146 m) · hardiness zone 6b*

  • Lower-risk planting dateafter April 30only 1 spring in 10 still has a frost later
  • Typical last frostApril 1350% chance of a frost after it
  • Typical first fall frostOctober 2550% chance of a frost before it
  • Frost-free season194 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Princeton, INSpring: a frost after March 29 in 9 years out of 10, after April 13 in half of the years, after April 30 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 25 in half of the years, before November 6 in 9 years out of 10. Typical frost-free season: 194 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 13First frost ~Oct 25Frost season at Princeton, INSpring: a frost after March 29 in 9 years out of 10, after April 13 in half of the years, after April 30 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 25 in half of the years, before November 6 in 9 years out of 10. Typical frost-free season: 194 days.JFMAMJJASONDLast frost ~Apr 13First frost ~Oct 25
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)April 30October 10
50% (typical)April 13October 25
90% (likely)March 29November 6
Frost-free season (32°F, 50% chance)
194 days
Hard frost (28°F), last in spring, 50% chance after
April 2
Hard frost (28°F), first in fall, 50% chance before
November 3

The last 15 years (2006–2020 normals)

Typical last frost April 10 (3 days earlier than the 30-year normal), typical first fall frost October 30 (5 days later). Frost-free season 199 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 Princeton: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 30, 20% April 24, 30% April 19, 40% April 16, 50% April 13, 60% April 9, 70% April 6, 80% April 2, 90% March 29. Observed last spring frost in recent years: 2021 April 23, 2022 April 20, 2024 April 6, 2025 April 9, 2026 March 28.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 30Apr 13Mar 292021: April 232022: April 202024: April 62025: April 92026: March 28Fall at Princeton: chance of a frost before this dateFall, chance of a frost before the date: 10% October 10, 20% October 17, 30% October 20, 40% October 23, 50% October 25, 60% October 28, 70% October 30, 80% November 2, 90% November 6. Observed first fall frost in recent years: 2021 November 3, 2024 November 26, 2025 November 10.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Dec 1Oct 10Oct 25Nov 62021: November 32024: November 262025: November 10
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 3
2022April 20incomplete record
2023incomplete recordno data
2024April 6November 26
2025April 9November 10
2026March 28season not over yet

What these dates mean

The cautious fall date in Princeton for finishing the harvest is October 10, when there is only a 10 % chance of a light frost earlier than that day.

For a gardener, the 50 % dates are the points at which a light frost is equally likely to have occurred or not. The median spring date is April 13 and the median fall date is October 25; these dates are not frost thresholds but simply the mid-point of the historical record. A cautious planting schedule therefore uses the April 30 date, which carries a 10 % chance of a later frost, for setting out tender crops in spring, and the October 10 date for completing tender-crop harvest in fall.

A hard frost at 28 °F can cause more severe damage than a light frost at 32 °F, so the April 2 and November 3 hard-frost median dates are important reference points.

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 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 Princeton, INNumbered nearest stations: 1 — Evansville, IN — 22 mi; 2 — Vincennes, IN — 27 mi; 3 — Boonville, IN — 28 mi; 4 — Mount Vernon, IN — 34 mi; 5 — Olney, IL — 36 mi.ILINKY25 mi · 40 km1. Evansville, IN — 22 mi12. Vincennes, IN — 27 mi23. Boonville, IN — 28 mi34. Mount Vernon, IN — 34 mi45. Olney, IL — 36 mi5
  1. Evansville, IN 22 mi (35 km)
  2. Vincennes, IN 27 mi (43 km)
  3. Boonville, IN 28 mi (46 km)
  4. Mount Vernon, IN 34 mi (55 km)
  5. Olney, IL 36 mi (57 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: 38.3567, -87.5906.