U.S. Frost Dates by Weather Station

NOAA station USC00106542 · Idaho

Frost Dates for Oakley, ID

NOAA weather station Oakley (USC00106542), Idaho · elevation 4559 ft (1390 m) · hardiness zone 6b*

  • Lower-risk planting dateafter June 6only 1 spring in 10 still has a frost later
  • Typical last frostMay 1550% chance of a frost after it
  • Typical first fall frostOctober 250% chance of a frost before it
  • Frost-free season137 daystypical year, 32°F
  • Hardiness zone6bcalculated*

The year at a glance

Frost season at Oakley, IDSpring: a frost after April 30 in 9 years out of 10, after May 15 in half of the years, after June 6 in 1 year out of 10. Fall: the first frost comes before September 16 in 1 year out of 10, before October 2 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 137 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 15First frost ~Oct 2Frost season at Oakley, IDSpring: a frost after April 30 in 9 years out of 10, after May 15 in half of the years, after June 6 in 1 year out of 10. Fall: the first frost comes before September 16 in 1 year out of 10, before October 2 in half of the years, before October 17 in 9 years out of 10. Typical frost-free season: 137 days.JFMAMJJASONDLast frost ~May 15First 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)June 6September 16
50% (typical)May 15October 2
90% (likely)April 30October 17
Frost-free season (32°F, 50% chance)
137 days
Hard frost (28°F), last in spring, 50% chance after
April 30
Hard frost (28°F), first in fall, 50% chance before
October 16

The last 15 years (2006–2020 normals)

Typical last frost May 13 (2 days earlier than the 30-year normal), typical first fall frost October 6 (4 days later). Frost-free season 145 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 Oakley: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 6, 20% May 30, 30% May 23, 40% May 18, 50% May 15, 60% May 12, 70% May 8, 80% May 4, 90% April 30. Observed last spring frost in recent years: 2021 May 11, 2023 April 23, 2024 May 9, 2025 May 7, 2026 May 18.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 6May 15Apr 302021: May 112023: April 232024: May 92025: May 72026: May 18Fall at Oakley: chance of a frost before this dateFall, chance of a frost before the date: 10% September 16, 20% September 22, 30% September 26, 40% September 29, 50% October 2, 60% October 6, 70% October 10, 80% October 13, 90% October 17. Observed first fall frost in recent years: 2021 September 29, 2023 October 26, 2024 October 18, 2025 October 28.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 16Oct 2Oct 172021: September 292023: October 262024: 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
2021May 11September 29
2022incomplete recordincomplete record
2023April 23October 26
2024May 9October 18
2025May 7October 28
2026May 18season not over yet

What these dates mean

September 16 is the cautious fall date for finishing the harvest in Oakley; there is only a 10 % chance that a light frost has arrived by then, making it the prudent deadline for tender crops.

For spring planting, the cautious date is June 6, when the chance of a light frost later is just 10 %; the 50% date is May 15, indicating a 50 % chance of a frost later than this date, while April 30 carries a 90 % chance and is a gamble. In the fall, the cautious date is September 16, the 50% date is October 2, indicating a 50 % chance of a frost earlier than this date, and October 17 bears a 90 % chance and is a gamble for late tender crops.

A hard frost at 28 °F can damage plants more severely than a light frost at 32 °F, so the median hard-frost dates of April 30 and October 16 are key reference points for gardeners.

How to read the probabilities

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

  • Spring: "10% after June 6" 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 16" 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 Oakley, IDNumbered nearest stations: 1 — Burley, ID — 22 mi; 2 — Paul, ID — 27 mi; 3 — Hazelton, ID — 28 mi; 4 — Minidoka Dam, ID — 37 mi; 5 — Shoshone, ID — 55 mi.UT25 mi · 40 km1. Burley, ID — 22 mi12. Paul, ID — 27 mi23. Hazelton, ID — 28 mi34. Minidoka Dam, ID — 37 mi45. Shoshone, ID — 55 mi5
  1. Burley, ID 22 mi (36 km)
  2. Paul, ID 27 mi (43 km)
  3. Hazelton, ID 28 mi (45 km)
  4. Minidoka Dam, ID 37 mi (59 km)
  5. Shoshone, ID 55 mi (89 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: 42.2342, -113.8981.