U.S. Frost Dates by Weather Station

NOAA station USC00131954 · Iowa

Frost Dates for Cresco, IA

NOAA weather station Cresco 1 NE (USC00131954), Iowa · elevation 1255 ft (383 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 21only 1 spring in 10 still has a frost later
  • Typical last frostMay 850% chance of a frost after it
  • Typical first fall frostOctober 150% chance of a frost before it
  • Frost-free season147 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Cresco, IASpring: a frost after April 25 in 9 years out of 10, after May 8 in half of the years, after May 21 in 1 year out of 10. Fall: the first frost comes before September 19 in 1 year out of 10, before October 1 in half of the years, before October 14 in 9 years out of 10. Typical frost-free season: 147 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 8First frost ~Oct 1Frost season at Cresco, IASpring: a frost after April 25 in 9 years out of 10, after May 8 in half of the years, after May 21 in 1 year out of 10. Fall: the first frost comes before September 19 in 1 year out of 10, before October 1 in half of the years, before October 14 in 9 years out of 10. Typical frost-free season: 147 days.JFMAMJJASONDLast frost ~May 8First frost ~Oct 1
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.Today

Frost dates (32°F)

Probability of frost, based on 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 21September 19
50% (typical)May 8October 1
90% (likely)April 25October 14
Frost-free season (32°F, 50% chance)
147 days
Hard frost (28°F), last in spring, 50% chance after
April 29
Hard frost (28°F), first in fall, 50% chance before
October 11

The last 15 years (2006–2020 normals)

Typical last frost May 6 (2 days earlier than the 30-year normal), typical first fall frost October 5 (4 days later). Frost-free season 150 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 Cresco: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 21, 20% May 17, 30% May 14, 40% May 10, 50% May 8, 60% May 5, 70% May 3, 80% April 30, 90% April 25.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 21May 8Apr 25Fall at Cresco: chance of a frost before this dateFall, chance of a frost before the date: 10% September 19, 20% September 24, 30% September 27, 40% September 30, 50% October 1, 60% October 4, 70% October 6, 80% October 10, 90% October 14.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 19Oct 1Oct 14
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

September 19 is the cautious fall date in Cresco for finishing the harvest of tender crops. The 50% light-frost date in autumn is October 1, indicating an even chance that a frost will arrive earlier than that day.

In spring the 50% light-frost date is May 8, meaning a gardener faces a 50 % chance of a frost later than this date. The 50% hard-frost dates are April 29 and October 11, each marking an even likelihood of a hard frost at 28 °F. The cautious spring date for setting out tender crops is May 21, when only a 10 % chance of a later frost remains.

A hard frost at 28 °F can cause damage that a light frost at 32 °F does not, so the hard-frost dates represent a higher risk level.

How to read the probabilities

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

  • Spring: "10% after May 21" 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 September 19" 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 Cresco, IANumbered nearest stations: 1 — Decorah, IA — 16 mi; 2 — Preston, MN — 20 mi; 3 — New Hampton, IA — 26 mi; 4 — Grand Meadow, MN — 32 mi; 5 — Rushford, MN — 33 mi.MNWI25 mi · 40 km1. Decorah, IA — 16 mi12. Preston, MN — 20 mi23. New Hampton, IA — 26 mi34. Grand Meadow, MN — 32 mi45. Rushford, MN — 33 mi5
  1. Decorah, IA 16 mi (26 km)
  2. Preston, MN 20 mi (32 km)
  3. New Hampton, IA 26 mi (42 km)
  4. Grand Meadow, MN 32 mi (52 km)
  5. Rushford, MN 33 mi (54 km)

Sources

* Hardiness zone 4b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 43.3894, -92.0939.