U.S. Frost Dates by Weather Station

NOAA station USW00014897 · Wisconsin

Frost Dates near Wausau, WI

NOAA weather station Wausau DWTN Airport (USW00014897), Wisconsin · elevation 1181 ft (360 m) · hardiness zone 5a*

Wausau is the nearest town to the station (2.3 mi away) in GeoNames (CC BY 4.0). The dates below are measured at the station, not in the town itself.

  • Lower-risk planting dateafter May 21only 1 spring in 10 still has a frost later
  • Typical last frostMay 650% chance of a frost after it
  • Typical first fall frostOctober 450% chance of a frost before it
  • Frost-free season150 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season near Wausau, WISpring: a frost after April 24 in 9 years out of 10, after May 6 in half of the years, after May 21 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 4 in half of the years, before October 18 in 9 years out of 10. Typical frost-free season: 150 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 6First frost ~Oct 4Frost season near Wausau, WISpring: a frost after April 24 in 9 years out of 10, after May 6 in half of the years, after May 21 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 4 in half of the years, before October 18 in 9 years out of 10. Typical frost-free season: 150 days.JFMAMJJASONDLast frost ~May 6First frost ~Oct 4
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 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 21September 21
50% (typical)May 6October 4
90% (likely)April 24October 18
Frost-free season (32°F, 50% chance)
150 days
Hard frost (28°F), last in spring, 50% chance after
April 26
Hard frost (28°F), first in fall, 50% chance before
October 16

The last 15 years (2006–2020 normals)

Typical last frost May 4 (2 days earlier than the 30-year normal), typical first fall frost October 9 (5 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 near Wausau: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 21, 20% May 17, 30% May 12, 40% May 8, 50% May 6, 60% May 4, 70% May 1, 80% April 28, 90% April 24. Observed last spring frost in recent years: 2021 May 12, 2022 May 4, 2023 May 3, 2024 April 25, 2025 April 22, 2026 May 11.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 21May 6Apr 242021: May 122022: May 42023: May 32024: April 252025: April 222026: May 11Fall near Wausau: chance of a frost before this dateFall, chance of a frost before the date: 10% September 21, 20% September 26, 30% September 29, 40% October 1, 50% October 4, 60% October 6, 70% October 9, 80% October 12, 90% October 18. Observed first fall frost in recent years: 2021 October 22, 2022 October 8, 2023 October 16, 2024 October 15, 2025 October 20.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 21Oct 4Oct 182021: October 222022: October 82023: October 162024: October 152025: October 20
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 12October 22
2022May 4October 8
2023May 3October 16
2024April 25October 15
2025April 22October 20
2026May 11season not over yet

What these dates mean

May 21 is the cautious spring date in the Wausau area and it allows a gardener to set out tender crops with only a 10% chance of a later light frost. Planting after this date gives the lowest risk of a frost interrupting early growth.

The 50% date in spring is May 6, which carries a 50% chance of a frost later than this date; the 50% date in fall is October 4, which carries a 50% chance of a frost earlier than this date. September 21 is the cautious fall date and marks the point when there is only a 10% chance a light frost has arrived, allowing a gardener to finish harvesting tender crops.

Hard frost at 28 °F, which reaches its 50% dates of April 26 in spring and October 16 in fall, can damage plants that survive a 32 °F light frost, making it a more critical threshold.

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 21" 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 Wausau, WINumbered nearest stations: 1 — Merrill, WI — 18 mi; 2 — Rosholt, WI — 22 mi; 3 — Stevens Point, WI — 29 mi; 4 — Marshfield, WI — 32 mi; 5 — Medford, WI — 38 mi.25 mi · 40 km1. Merrill, WI — 18 mi12. Rosholt, WI — 22 mi23. Stevens Point, WI — 29 mi34. Marshfield, WI — 32 mi45. Medford, WI — 38 mi5
  1. Merrill, WI 18 mi (28 km)
  2. Rosholt, WI 22 mi (36 km)
  3. Stevens Point, WI 29 mi (46 km)
  4. Marshfield, WI 32 mi (51 km)
  5. Medford, WI 38 mi (61 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: 44.9258, -89.6256.