U.S. Frost Dates by Weather Station

NOAA station USC00124244 · Indiana

Frost Dates for Indiana Dunes NL, IN

NOAA weather station Indiana Dunes NL (USC00124244), Indiana · elevation 680 ft (207 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 8only 1 spring in 10 still has a frost later
  • Typical last frostApril 2250% chance of a frost after it
  • Typical first fall frostOctober 2750% chance of a frost before it
  • Frost-free season188 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Indiana Dunes NL, INSpring: a frost after April 7 in 9 years out of 10, after April 22 in half of the years, after May 8 in 1 year out of 10. Fall: the first frost comes before October 15 in 1 year out of 10, before October 27 in half of the years, before November 9 in 9 years out of 10. Typical frost-free season: 188 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 22First frost ~Oct 27Frost season at Indiana Dunes NL, INSpring: a frost after April 7 in 9 years out of 10, after April 22 in half of the years, after May 8 in 1 year out of 10. Fall: the first frost comes before October 15 in 1 year out of 10, before October 27 in half of the years, before November 9 in 9 years out of 10. Typical frost-free season: 188 days.JFMAMJJASONDLast frost ~Apr 22First frost ~Oct 27
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 27 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 8October 15
50% (typical)April 22October 27
90% (likely)April 7November 9
Frost-free season (32°F, 50% chance)
188 days
Hard frost (28°F), last in spring, 50% chance after
April 8
Hard frost (28°F), first in fall, 50% chance before
November 7

The last 15 years (2006–2020 normals)

Typical last frost April 21 (1 day earlier than the 30-year normal), typical first fall frost October 30 (3 days later). Frost-free season 191 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 Indiana Dunes NL: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 8, 20% May 2, 30% April 29, 40% April 25, 50% April 22, 60% April 19, 70% April 16, 80% April 12, 90% April 7. Observed last spring frost in recent years: 2022 April 19, 2023 May 3, 2024 April 26, 2025 April 1, 2026 May 2.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 8Apr 22Apr 72022: April 192023: May 32024: April 262025: April 12026: May 2Fall at Indiana Dunes NL: chance of a frost before this dateFall, chance of a frost before the date: 10% October 15, 20% October 20, 30% October 22, 40% October 25, 50% October 27, 60% October 30, 70% November 1, 80% November 4, 90% November 9. Observed first fall frost in recent years: 2022 October 9, 2023 October 31, 2024 November 21.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 15Oct 27Nov 92022: October 92023: October 312024: November 21
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
2021incomplete recordincomplete record
2022April 19October 9
2023May 3October 31
2024April 26November 21
2025April 1incomplete record
2026May 2season not over yet

What these dates mean

May 8, with only a 10% chance of a light frost later, is the cautious date for setting out tender crops at Indiana Dunes NL. This timing lets a gardener move seedlings outdoors while the risk of damaging frost remains low.

The 50% date of April 22 in spring and October 27 in fall mark the moment a light frost is equally likely to have occurred or not. October 15, with a 10% chance of a light frost earlier, is the cautious fall date for finishing tender-crop harvests. The two 32°F 50% dates are 188 days apart, reflecting the span between equal odds of a light frost in spring and fall. Hard-frost 50% dates are April 8 and November 7, and hard frosts matter more because 28 °F can kill many plant tissues.

How to read the probabilities

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

  • Spring: "10% after May 8" 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 15" 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 Indiana Dunes NL, INNumbered nearest stations: 1 — Wanatah, IN — 15 mi; 2 — Laporte, IN — 19 mi; 3 — Lowell, IN — 31 mi; 4 — Park Forest, IL — 32 mi; 5 — near Chicago, IL — 36 mi.INILMI25 mi · 40 km1. Wanatah, IN — 15 mi12. Laporte, IN — 19 mi23. Lowell, IN — 31 mi34. Park Forest, IL — 32 mi45. near Chicago, IL — 36 mi5
  1. Wanatah, IN 15 mi (25 km)
  2. Laporte, IN 19 mi (30 km)
  3. Lowell, IN 31 mi (49 km)
  4. Park Forest, IL 32 mi (52 km)
  5. near Chicago, IL 36 mi (58 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: 41.6317, -87.0881.