U.S. Frost Dates by Weather Station

NOAA station USC00477132 · Wisconsin

Frost Dates for Rice Lake, WI

NOAA weather station Rice Lake (USC00477132), Wisconsin · elevation 1103 ft (336 m) · hardiness zone 4b*

  • Lower-risk planting dateafter May 23only 1 spring in 10 still has a frost later
  • Typical last frostMay 850% chance of a frost after it
  • Typical first fall frostOctober 250% chance of a frost before it
  • Frost-free season145 daystypical year, 32°F
  • Hardiness zone4bcalculated*

The year at a glance

Frost season at Rice Lake, WISpring: a frost after April 25 in 9 years out of 10, after May 8 in half of the years, after May 23 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 14 in 9 years out of 10. Typical frost-free season: 145 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 8First frost ~Oct 2Frost season at Rice Lake, WISpring: a frost after April 25 in 9 years out of 10, after May 8 in half of the years, after May 23 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 14 in 9 years out of 10. Typical frost-free season: 145 days.JFMAMJJASONDLast frost ~May 8First 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 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 23September 19
50% (typical)May 8October 2
90% (likely)April 25October 14
Frost-free season (32°F, 50% chance)
145 days
Hard frost (28°F), last in spring, 50% chance after
April 28
Hard frost (28°F), first in fall, 50% chance before
October 11

The last 15 years (2006–2020 normals)

Typical last frost May 7 (1 day earlier than the 30-year normal), typical first fall frost October 3 (1 day 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 Rice Lake: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 23, 20% May 18, 30% May 14, 40% May 11, 50% May 8, 60% May 5, 70% May 2, 80% April 29, 90% April 25. Observed last spring frost in recent years: 2021 May 12, 2022 May 5, 2023 May 3, 2026 May 12.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1May 23May 8Apr 252021: May 122022: May 52023: May 32026: May 12Fall at Rice Lake: chance of a frost before this dateFall, chance of a frost before the date: 10% September 19, 20% September 24, 30% September 27, 40% September 30, 50% October 2, 60% October 4, 70% October 6, 80% October 9, 90% October 14. Observed first fall frost in recent years: 2021 September 25, 2022 September 28, 2023 October 17, 2025 October 8.Fall: first frostChance of a frost before this date10%50%90%Oct 1Sep 19Oct 2Oct 142021: September 252022: September 282023: October 172025: October 8
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 12September 25
2022May 5September 28
2023May 3October 17
2024incomplete recordincomplete record
2025incomplete recordOctober 8
2026May 12season not over yet

What these dates mean

May 23 is the cautious spring light-frost date for Rice Lake, carrying only a 10 % chance that a 32 °F frost will occur later; it is the point at which a gardener can plan to set out tender crops with minimal risk. The 50 % spring date, May 8, marks the median moment when a light frost is just as likely as not, while the hard-frost 50 % date, April 28, indicates an even chance of a 28 °F event that can damage more vulnerable tissue.

In the fall, September 19 is the cautious light-frost date, having only a 10 % chance that a 32 °F frost will have arrived earlier, so it signals when tender crops should be finished harvesting. The median light-frost date, October 2, splits the odds of a frost, and the hard-frost 50 % date, October 11, shows the midpoint for a more severe 28 °F freeze.

A hard frost at 28 °F can injure plant tissue that survives a light frost at 32 °F, making its timing especially important for growers.

How to read the probabilities

The dates are probabilities from 30 years of weather, not a forecast for this year.

  • Spring: "10% after May 23" 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 Rice Lake, WINumbered nearest stations: 1 — Cumberland, WI — 15 mi; 2 — Ridgeland, WI — 15 mi; 3 — Bloomer, WI — 26 mi; 4 — Spooner, WI — 29 mi; 5 — Amery, WI — 30 mi.WIMN25 mi · 40 km1. Cumberland, WI — 15 mi12. Ridgeland, WI — 15 mi23. Bloomer, WI — 26 mi34. Spooner, WI — 29 mi45. Amery, WI — 30 mi5
  1. Cumberland, WI 15 mi (23 km)
  2. Ridgeland, WI 15 mi (24 km)
  3. Bloomer, WI 26 mi (43 km)
  4. Spooner, WI 29 mi (46 km)
  5. Amery, WI 30 mi (48 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: 45.4167, -91.7725.