U.S. Frost Dates by Weather Station

NOAA station USC00108380 · Idaho

Frost Dates for Shoshone, ID

NOAA weather station Shoshone 1 WNW (USC00108380), Idaho · elevation 3950 ft (1204 m) · hardiness zone 6b*

  • Lower-risk planting dateafter May 12only 1 spring in 10 still has a frost later
  • Typical last frostApril 2450% chance of a frost after it
  • Typical first fall frostOctober 1650% chance of a frost before it
  • Frost-free season173 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Shoshone, IDSpring: a frost after April 9 in 9 years out of 10, after April 24 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 2 in 1 year out of 10, before October 16 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 173 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 24First frost ~Oct 16Frost season at Shoshone, IDSpring: a frost after April 9 in 9 years out of 10, after April 24 in half of the years, after May 12 in 1 year out of 10. Fall: the first frost comes before October 2 in 1 year out of 10, before October 16 in half of the years, before November 1 in 9 years out of 10. Typical frost-free season: 173 days.JFMAMJJASONDLast frost ~Apr 24First frost ~Oct 16
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 12October 2
50% (typical)April 24October 16
90% (likely)April 9November 1
Frost-free season (32°F, 50% chance)
173 days
Hard frost (28°F), last in spring, 50% chance after
April 9
Hard frost (28°F), first in fall, 50% chance before
October 26

The last 15 years (2006–2020 normals)

Typical last frost May 2 (8 days later than the 30-year normal), typical first fall frost October 10 (6 days earlier). Frost-free season 158 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 Shoshone: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 12, 20% May 5, 30% May 1, 40% April 28, 50% April 24, 60% April 21, 70% April 18, 80% April 14, 90% April 9. Observed last spring frost in recent years: 2021 April 20, 2022 May 19, 2023 April 20, 2024 May 2, 2025 April 19, 2026 May 17.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1May 12Apr 24Apr 92021: April 202022: May 192023: April 202024: May 22025: April 192026: May 17Fall at Shoshone: chance of a frost before this dateFall, chance of a frost before the date: 10% October 2, 20% October 6, 30% October 10, 40% October 13, 50% October 16, 60% October 19, 70% October 21, 80% October 25, 90% November 1. Observed first fall frost in recent years: 2021 October 12, 2022 October 23, 2023 October 27, 2024 October 18, 2025 October 28.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 2Oct 16Nov 12021: October 122022: October 232023: October 272024: October 182025: October 28
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
2021April 20October 12
2022May 19October 23
2023April 20October 27
2024May 2October 18
2025April 19October 28
2026May 17season not over yet

What these dates mean

October 2 is the cautious fall date to finish harvesting tender crops in Shoshone, carrying only a 10 % chance that a light frost has arrived earlier. In spring the cautious date for setting out tender crops is May 12, when the probability of a light frost later than that date is also 10 %. The 50% dates provide a neutral reference: the spring 50% date is April 24, marking a point where there is a 50 % chance of a light frost later than that date, and the fall 50% date is October 16, where there is a 50 % chance of a light frost earlier. Gardeners can use these benchmarks to gauge risk over the 26-year record. A hard frost at 28 °F is more damaging than a light frost at 32 °F, so the hard-frost 50% dates—April 9 in spring and October 26 in fall—are especially important to watch.

How to read the probabilities

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

  • Spring: "10% after May 12" 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 October 2" 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 Shoshone, IDNumbered nearest stations: 1 — Richfield, ID — 15 mi; 2 — Hazelton, ID — 27 mi; 3 — Paul, ID — 40 mi; 4 — Burley, ID — 43 mi; 5 — Minidoka Dam, ID — 50 mi.ID25 mi · 40 km1. Richfield, ID — 15 mi12. Hazelton, ID — 27 mi23. Paul, ID — 40 mi34. Burley, ID — 43 mi45. Minidoka Dam, ID — 50 mi5
  1. Richfield, ID 15 mi (25 km)
  2. Hazelton, ID 27 mi (44 km)
  3. Paul, ID 40 mi (65 km)
  4. Burley, ID 43 mi (69 km)
  5. Minidoka Dam, ID 50 mi (80 km)

Sources

* Hardiness zone 6b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 42.9383, -114.4169.