U.S. Frost Dates by Weather Station

NOAA station USC00334942 · Ohio

Frost Dates for Marion, OH

NOAA weather station Marion 2 N (USC00334942), Ohio · elevation 965 ft (294 m) · hardiness zone 6a*

  • Lower-risk planting dateafter May 11only 1 spring in 10 still has a frost later
  • Typical last frostApril 2550% chance of a frost after it
  • Typical first fall frostOctober 2050% chance of a frost before it
  • Frost-free season178 daystypical year, 32°F
  • Hardiness zone6acalculated*

The year at a glance

Frost season at Marion, OHSpring: a frost after April 11 in 9 years out of 10, after April 25 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 20 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 178 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 25First frost ~Oct 20Frost season at Marion, OHSpring: a frost after April 11 in 9 years out of 10, after April 25 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 20 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 178 days.JFMAMJJASONDLast frost ~Apr 25First frost ~Oct 20
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)May 11October 5
50% (typical)April 25October 20
90% (likely)April 11November 2
Frost-free season (32°F, 50% chance)
178 days
Hard frost (28°F), last in spring, 50% chance after
April 14
Hard frost (28°F), first in fall, 50% chance before
November 1

The last 15 years (2006–2020 normals)

Typical last frost April 23 (2 days earlier than the 30-year normal), typical first fall frost October 22 (2 days later). Frost-free season 180 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 Marion: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 11, 20% May 6, 30% May 2, 40% April 28, 50% April 25, 60% April 22, 70% April 19, 80% April 16, 90% April 11.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 11Apr 25Apr 11Fall at Marion: chance of a frost before this dateFall, chance of a frost before the date: 10% October 5, 20% October 11, 30% October 14, 40% October 17, 50% October 20, 60% October 23, 70% October 26, 80% October 29, 90% November 2.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 5Oct 20Nov 2
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.

What these dates mean

In Marion the two 32°F 50% dates are spaced 178 days apart, defining the core window between April 25 and October 20 in which light frosts are less likely to intervene. The 50% date in spring, April 25, marks the point where there is an even chance of a light frost occurring later, while the fall 50% date, October 20, marks the point where there is an even chance of a light frost having occurred earlier.

A cautious plan for tender crops would wait until May 11, which carries only a 10% chance of a later light frost, and would aim to finish harvesting by October 5, which carries only a 10% chance of an earlier light frost. Starting out on April 11 or counting on crops through November 2 would be a gamble, because each of those dates carries a 90% chance of frost in the opposite direction.

Hard frosts at 28°F, reflected by the median dates April 14 and November 1, can damage plants that survive a 32°F light frost, making them a more severe threat.

How to read the probabilities

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

  • Spring: "10% after May 11" 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 5" 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 Marion, OHNumbered nearest stations: 1 — Bucyrus, OH — 16 mi; 2 — Marysville, OH — 30 mi; 3 — Centerburg, OH — 34 mi; 4 — near Mansfield, OH — 35 mi; 5 — Westerville, OH — 35 mi.OH25 mi · 40 km1. Bucyrus, OH — 16 mi12. Marysville, OH — 30 mi23. Centerburg, OH — 34 mi34. near Mansfield, OH — 35 mi45. Westerville, OH — 35 mi5
  1. Bucyrus, OH 16 mi (26 km)
  2. Marysville, OH 30 mi (48 km)
  3. Centerburg, OH 34 mi (54 km)
  4. near Mansfield, OH 35 mi (57 km)
  5. Westerville, OH 35 mi (57 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: 40.6167, -83.1333.