Frost dates 2026–2027

Frost dates for Blackfoot, Idaho

Median (50% chance) dates of the last and first 32°F frost, from NOAA 1991–2020 climate normals at Blackfoot Fire Dept, 0.2 mi away (close match).

Last spring frostMay 5
First fall frostOct 3
149 frost-free days
Last spring frostMay 51 year in 10 after May 22
First fall frostOct 31 year in 10 by Sep 16
Growing season149 daysbetween median 32°F dates
Hardiness zoneZone 5b−15 to −10°F average extreme low

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Will it freeze in Blackfoot in the next 7 nights?

The earliest overnight low at or below 32°F in the available NWS frost forecast is Tonight: 28°F (Thu, Nov 5, 6:00 PM MST to Fri, Nov 6, 6:00 AM MST).

Tonight: forecast low 28°F. Hard freeze.

NWS forecast period: Thu, Nov 5, 6:00 PM MST to Fri, Nov 6, 6:00 AM MST.

7 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.

Overnight lows from the National Weather Service forecast for this location. This covers the available forecast window, not the first freeze of the whole season. Frost can form above 32°F on clear, calm nights.

Frost and freeze probabilities

Freeze dates shift from year to year. Spring percentages describe the chance of a freeze after the stated date; fall percentages describe the chance of a freeze by that date. The 10% spring date is the cautious one: a later freeze happens about 1 year in 10.

These dates describe historical probabilities, not this year’s forecast or the earliest and latest possible freezes. Different weather stations or probability thresholds can produce different published dates for the same city.

Average first hard freeze in Blackfoot

The median first fall hard-freeze date (28°F) is October 16, from NOAA’s 1991–2020 Climate Normals at Blackfoot Fire Dept. This is the 50% probability date, not a forecast for this year.

TemperatureLast spring date
90% · 50% · 10% chance of a later freeze
First fall date
10% · 50% · 90% chance of an earlier freeze
Season
36°F frost possible May 8 · May 23 · Jun 14 Sep 4 · Sep 21 · Oct 5 118 days
32°F freeze Apr 23 · May 5 · May 22 Sep 16 · Oct 3 · Oct 18 149 days
28°F hard freeze Apr 6 · Apr 22 · May 4 Sep 30 · Oct 16 · Oct 31 176 days
NOAA NCEI U.S. Climate Normals 1991–2020, station USC00100915. How to read these probabilities.

Average high temperature by month

1991–2020 normals at Blackfoot Fire Dept

Average low temperature by month

Months with lows near or below freezing carry frost risk

Where these frost dates come from

The frost dates for Blackfoot, ID come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Blackfoot Fire Dept (station USC00100915, elevation 4,499 ft), 0.2 mi from Blackfoot. Local conditions (valleys, hilltops, distance to water, city heat) can shift frost dates by days or weeks. The hardiness zone is from the 2023 USDA Plant Hardiness Zone Map (USDA ARS and Oregon State University PRISM). See our methodology.

Frost dates near Blackfoot

CityDistanceLast spring frostFirst fall frost
Shelley, ID 17 mi May 23 Sep 20
Chubbuck, ID 19 mi May 16 Oct 2
Pocatello, ID 23 mi May 2 Oct 11
Idaho Falls, ID 25 mi May 9 Oct 1
Ammon, ID 27 mi May 9 Oct 1
Rigby, ID 40 mi May 9 Oct 5
Rexburg, ID 52 mi May 12 Sep 24
Rupert, ID 78 mi May 6 Oct 6
Preston, ID 80 mi May 16 Sep 28
Jackson, WY 81 mi Jun 20 Aug 31

Frequently asked questions

When is the last frost in Blackfoot?

On average, the last spring frost (32°F) in Blackfoot is around May 5. In about 1 year in 10 it comes after May 22, and in 9 years in 10 it comes after April 23.

When is the first frost in Blackfoot?

The first fall frost (32°F) usually arrives around October 3. There’s a 10% chance of a freeze by September 16 and a 90% chance by October 18.

Can it frost in Blackfoot after the last frost date?

Yes. Frost can form on clear, calm nights even when the air stays above 32°F. Temperatures of 36°F or lower, cold enough for frost on exposed plants, have a 50% chance of occurring after May 23.

What growing zone is Blackfoot?

Blackfoot is in USDA Plant Hardiness Zone 5b (average annual extreme minimum temperature −15 to −10°F), based on the 2023 USDA map for ZIP code 83221. See growing zones in Idaho.

More: all Idaho frost dates · Idaho growing zones · frost vs. freeze