U.S. Frost Dates by Weather Station

NOAA station USC00130753 · Iowa

Frost Dates for Bloomfield, IA

NOAA weather station Bloomfield (USC00130753), Iowa · elevation 858 ft (262 m) · hardiness zone 5b*

  • Lower-risk planting dateafter April 30only 1 spring in 10 still has a frost later
  • Typical last frostApril 1650% chance of a frost after it
  • Typical first fall frostOctober 2250% chance of a frost before it
  • Frost-free season188 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Bloomfield, IASpring: a frost after April 1 in 9 years out of 10, after April 16 in half of the years, after April 30 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 22 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 188 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 16First frost ~Oct 22Frost season at Bloomfield, IASpring: a frost after April 1 in 9 years out of 10, after April 16 in half of the years, after April 30 in 1 year out of 10. Fall: the first frost comes before October 5 in 1 year out of 10, before October 22 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 188 days.JFMAMJJASONDLast frost ~Apr 16First frost ~Oct 22
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)April 30October 5
50% (typical)April 16October 22
90% (likely)April 1November 2
Frost-free season (32°F, 50% chance)
188 days
Hard frost (28°F), last in spring, 50% chance after
April 6
Hard frost (28°F), first in fall, 50% chance before
October 31

The last 15 years (2006–2020 normals)

Typical last frost April 20 (4 days later than the 30-year normal), typical first fall frost October 23 (1 day later). Frost-free season 187 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 Bloomfield: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 30, 20% April 26, 30% April 23, 40% April 19, 50% April 16, 60% April 13, 70% April 10, 80% April 6, 90% April 1.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 30Apr 16Apr 1Fall at Bloomfield: chance of a frost before this dateFall, chance of a frost before the date: 10% October 5, 20% October 12, 30% October 16, 40% October 19, 50% October 22, 60% October 24, 70% October 27, 80% October 30, 90% November 2.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 5Oct 22Nov 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

Setting out tender crops on the early spring date of April 1 in Bloomfield carries a 90 % chance that a light frost will still occur later that season. The opposite extreme, April 30, is the cautious spring date with only a 10 % chance of a later frost, while planting after that date is far less risky.

For a Bloomfield gardener the 50 % dates are markers of even odds: April 16 marks the point at which a light frost is as likely as not later in spring, and October 22 marks the point at which a light frost is as likely as not earlier in fall. The cautious plan for tender crops therefore uses April 30 to start planting in spring and October 5 to finish harvesting in fall, each carrying only a 10 % frost risk.

A hard frost at 28 °F, such as the median dates of April 6 and October 31, can damage plants more severely than a light frost at 32 °F.

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 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 Bloomfield, IANumbered nearest stations: 1 — Keosauqua, IA — 23 mi; 2 — near Ottumwa, IA — 26 mi; 3 — Albia, IA — 30 mi; 4 — Fairfield, IA — 31 mi; 5 — Kirksville, MO — 38 mi.IL25 mi · 40 km1. Keosauqua, IA — 23 mi12. near Ottumwa, IA — 26 mi23. Albia, IA — 30 mi34. Fairfield, IA — 31 mi45. Kirksville, MO — 38 mi5
  1. Keosauqua, IA 23 mi (37 km)
  2. near Ottumwa, IA 26 mi (41 km)
  3. Albia, IA 30 mi (48 km)
  4. Fairfield, IA 31 mi (50 km)
  5. Kirksville, MO 38 mi (61 km)

Sources

* Hardiness zone 5b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 40.7392, -92.4142.