U.S. Frost Dates by Weather Station

NOAA station USC00475563 · Wisconsin

Frost Dates for Mondovi, WI

NOAA weather station Mondovi (USC00475563), Wisconsin · elevation 830 ft (253 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 25only 1 spring in 10 still has a frost later
  • Typical last frostMay 1050% chance of a frost after it
  • Typical first fall frostOctober 250% chance of a frost before it
  • Frost-free season144 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Mondovi, WISpring: a frost after April 27 in 9 years out of 10, after May 10 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 19 in 1 year out of 10, before October 2 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 144 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 10First frost ~Oct 2Frost season at Mondovi, WISpring: a frost after April 27 in 9 years out of 10, after May 10 in half of the years, after May 25 in 1 year out of 10. Fall: the first frost comes before September 19 in 1 year out of 10, before October 2 in half of the years, before October 13 in 9 years out of 10. Typical frost-free season: 144 days.JFMAMJJASONDLast frost ~May 10First frost ~Oct 2
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 25September 19
50% (typical)May 10October 2
90% (likely)April 27October 13
Frost-free season (32°F, 50% chance)
144 days
Hard frost (28°F), last in spring, 50% chance after
April 30
Hard frost (28°F), first in fall, 50% chance before
October 9

The last 15 years (2006–2020 normals)

Typical last frost May 9 (1 day earlier than the 30-year normal), typical first fall frost October 4 (2 days later). Frost-free season 147 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 Mondovi: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 25, 20% May 19, 30% May 16, 40% May 13, 50% May 10, 60% May 7, 70% May 5, 80% May 1, 90% April 27. Observed last spring frost in recent years: 2021 May 29, 2022 May 23, 2023 May 20, 2024 May 6.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 25May 10Apr 272021: May 292022: May 232023: May 202024: May 6Fall at Mondovi: chance of a frost before this dateFall, chance of a frost before the date: 10% September 19, 20% September 23, 30% September 27, 40% September 30, 50% October 2, 60% October 4, 70% October 6, 80% October 9, 90% October 13. Observed first fall frost in recent years: 2021 October 17, 2022 September 27, 2023 September 14.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 19Oct 2Oct 132021: October 172022: September 272023: September 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. ◆ 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 29October 17
2022May 23September 27
2023May 20September 14
2024May 6incomplete record
2025incomplete recordincomplete record
2026incomplete recordseason not over yet

What these dates mean

May 25 is the cautious spring light-frost date for Mondovi; with only a 10 % chance of a frost later, a gardener can plan to set out tender crops on that day. The 90 % chance date of April 27 would be a gamble, while the median May 10 is a 50 % date that simply marks the point where a light frost is equally likely before or after it.

The 50 % light-frost dates—May 10 in spring and October 2 in fall—are not frost dates themselves; they indicate the day when the probability of a light frost is exactly even. Likewise, the hard-frost 50 % dates are April 30 for spring and October 9 for fall, showing when a 28 °F frost is equally probable.

September 19 serves as the cautious fall light-frost date, with only a 10 % chance that a frost has arrived earlier, allowing growers to finish harvesting tender crops. A hard frost at 28 °F can damage plants more severely than a light frost at 32 °F, so the hard-frost dates 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 25" 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 Mondovi, WINumbered nearest stations: 1 — near Alma, WI — 20 mi; 2 — Eau Claire, WI — 23 mi; 3 — Menomonie, WI — 25 mi; 4 — Theilman, MN — 32 mi; 5 — near Winona, MN — 33 mi.WIMN25 mi · 40 km1. near Alma, WI — 20 mi12. Eau Claire, WI — 23 mi23. Menomonie, WI — 25 mi34. Theilman, MN — 32 mi45. near Winona, MN — 33 mi5
  1. near Alma, WI 20 mi (33 km)
  2. Eau Claire, WI 23 mi (37 km)
  3. Menomonie, WI 25 mi (40 km)
  4. Theilman, MN 32 mi (52 km)
  5. near Winona, MN 33 mi (53 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: 44.5647, -91.6719.