U.S. Frost Dates by Weather Station

NOAA station USC00478951 · Wisconsin

Frost Dates for Waupaca, WI

NOAA weather station Waupaca (USC00478951), Wisconsin · elevation 837 ft (255 m) · hardiness zone 5a*

  • 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 650% chance of a frost before it
  • Frost-free season151 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Waupaca, WISpring: a frost after April 24 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 23 in 1 year out of 10, before October 6 in half of the years, before October 18 in 9 years out of 10. Typical frost-free season: 151 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 8First frost ~Oct 6Frost season at Waupaca, WISpring: a frost after April 24 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 23 in 1 year out of 10, before October 6 in half of the years, before October 18 in 9 years out of 10. Typical frost-free season: 151 days.JFMAMJJASONDLast frost ~May 8First frost ~Oct 6
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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 21September 23
50% (typical)May 8October 6
90% (likely)April 24October 18
Frost-free season (32°F, 50% chance)
151 days
Hard frost (28°F), last in spring, 50% chance after
April 28
Hard frost (28°F), first in fall, 50% chance before
October 17

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 9 (3 days later). Frost-free season 154 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 Waupaca: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 21, 20% May 16, 30% May 13, 40% May 10, 50% May 8, 60% May 4, 70% May 1, 80% April 29, 90% April 24. Observed last spring frost in recent years: 2021 May 8, 2022 April 29, 2023 May 3, 2024 April 26.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 21May 8Apr 242021: May 82022: April 292023: May 32024: April 26Fall at Waupaca: chance of a frost before this dateFall, chance of a frost before the date: 10% September 23, 20% September 28, 30% September 30, 40% October 3, 50% October 6, 60% October 8, 70% October 10, 80% October 14, 90% October 18. Observed first fall frost in recent years: 2021 October 22, 2022 October 19, 2023 October 22, 2024 October 16.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 23Oct 6Oct 182021: October 222022: October 192023: October 222024: October 16
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 29October 19
2023May 3October 22
2024April 26October 16
2025no datano data
2026no dataseason not over yet

What these dates mean

May 21 is the cautious spring date in Waupaca, allowing a gardener to set out tender crops with only a 10 % chance of a later frost.

The 50 % dates are April 28 and May 8 for spring, and October 6 and October 17 for fall; on each, there is an even chance of a frost occurring later in spring or earlier in fall. September 23 serves as the cautious fall date, giving a 10 % chance that a frost has already arrived, which guides the latest safe time to finish harvesting tender crops.

Hard frost at 28 °F can damage plant tissue more severely than a light frost at 32 °F, so its 50 % dates—April 28 in spring and October 17 in fall—are especially important for risk assessment.

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 23" 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 Waupaca, WINumbered nearest stations: 1 — New London, WI — 17 mi; 2 — Clintonville, WI — 24 mi; 3 — Stevens Point, WI — 28 mi; 4 — Hancock Experiment Farm, WI — 29 mi; 5 — Rosholt, WI — 29 mi.WI25 mi · 40 km1. New London, WI — 17 mi12. Clintonville, WI — 24 mi23. Stevens Point, WI — 28 mi34. Hancock Experiment Farm, WI — 29 mi45. Rosholt, WI — 29 mi5
  1. New London, WI 17 mi (27 km)
  2. Clintonville, WI 24 mi (39 km)
  3. Stevens Point, WI 28 mi (45 km)
  4. Hancock Experiment Farm, WI 29 mi (46 km)
  5. Rosholt, WI 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: 44.3547, -89.0594.