U.S. Frost Dates by Weather Station

NOAA station USW00014990 · Iowa

Frost Dates for Cedar Rapids, IA

NOAA weather station Cedar Rapids Municipal Airport (USW00014990), Iowa · elevation 868 ft (265 m) · hardiness zone 5a*

  • Lower-risk planting dateafter May 11only 1 spring in 10 still has a frost later
  • Typical last frostApril 2750% chance of a frost after it
  • Typical first fall frostOctober 1150% chance of a frost before it
  • Frost-free season165 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Cedar Rapids, IASpring: a frost after April 13 in 9 years out of 10, after April 27 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before September 25 in 1 year out of 10, before October 11 in half of the years, before October 23 in 9 years out of 10. Typical frost-free season: 165 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 27First frost ~Oct 11Frost season at Cedar Rapids, IASpring: a frost after April 13 in 9 years out of 10, after April 27 in half of the years, after May 11 in 1 year out of 10. Fall: the first frost comes before September 25 in 1 year out of 10, before October 11 in half of the years, before October 23 in 9 years out of 10. Typical frost-free season: 165 days.JFMAMJJASONDLast frost ~Apr 27First frost ~Oct 11
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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 11September 25
50% (typical)April 27October 11
90% (likely)April 13October 23
Frost-free season (32°F, 50% chance)
165 days
Hard frost (28°F), last in spring, 50% chance after
April 16
Hard frost (28°F), first in fall, 50% chance before
October 21

The last 15 years (2006–2020 normals)

Typical last frost April 28 (1 day later than the 30-year normal), typical first fall frost October 13 (2 days later). Frost-free season 167 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 Cedar Rapids: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 11, 20% May 6, 30% May 3, 40% April 30, 50% April 27, 60% April 24, 70% April 22, 80% April 17, 90% April 13. Observed last spring frost in recent years: 2021 May 8, 2022 April 26, 2023 April 26, 2024 April 22, 2025 April 8, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 11Apr 27Apr 132021: May 82022: April 262023: April 262024: April 222025: April 82026: May 7Fall at Cedar Rapids: chance of a frost before this dateFall, chance of a frost before the date: 10% September 25, 20% October 1, 30% October 5, 40% October 8, 50% October 11, 60% October 13, 70% October 16, 80% October 19, 90% October 23. Observed first fall frost in recent years: 2021 October 22, 2022 September 29, 2023 October 10, 2024 October 15.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 25Oct 11Oct 232021: October 222022: September 292023: October 102024: October 15
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
2021May 8October 22
2022April 26September 29
2023April 26October 10
2024April 22October 15
2025April 8incomplete record
2026May 7season not over yet

What these dates mean

Setting out tender crops on April 13 in Cedar Rapids carries a 90% chance of a frost later in the season, making it a gamble. The cautious spring date is May 11, when only a 10% chance remains.

In the fall, September 25 is the cautious date with a 10% chance of a frost earlier, while October 23 is a gamble with a 90% chance. For a gardener, the 50% date is April 27, marking an even chance of a light frost later, and the 50% date is October 11, marking an even chance of a light frost earlier. The 50% hard-frost date is April 16 and the 50% hard-frost date is October 21, highlighting when a 28 °F freeze becomes equally likely.

Hard frost at 28 °F 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 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 September 25" 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 Cedar Rapids, IANumbered nearest stations: 1 — near Marion, IA — 13 mi; 2 — Williamsburg, IA — 21 mi; 3 — Iowa City, IA — 22 mi; 4 — Vinton, IA — 25 mi; 5 — Belle Plaine, IA — 29 mi.IAILWI25 mi · 40 km1. near Marion, IA — 13 mi12. Williamsburg, IA — 21 mi23. Iowa City, IA — 22 mi34. Vinton, IA — 25 mi45. Belle Plaine, IA — 29 mi5
  1. near Marion, IA 13 mi (21 km)
  2. Williamsburg, IA 21 mi (34 km)
  3. Iowa City, IA 22 mi (35 km)
  4. Vinton, IA 25 mi (40 km)
  5. Belle Plaine, IA 29 mi (46 km)

Sources

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

Station coordinates: 41.8833, -91.7167.