USDA Hardiness Zone 7a

Frost Dates for 83617 — Emmett, Idaho

NOAA 1991–2020 normals from Emmett 2 E, ID (2,390 ft), 3 miles southeast.

Updated October 28, 2026

In Emmett, the last spring frost (32°F) is around April 30 in half of years and has passed by May 17 in nine years out of ten. The first fall frost comes around October 17, as early as October 2 one year in ten, leaving a typical freeze-free season of 168 days (NOAA, Emmett 2 E, ID).

Last spring frost: April 30
First fall frost: October 17
Growing season: 168 days
Hardiness zone: 7a

First snow: December 12
Last snow: February 20
Winters with snow: 67%
Snow per year: 7.4"

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Frost risk by date in Emmett

Half of springs at Emmett 2 E, ID see their last 32°F night by April 30; only one in ten is past it by April 17, and one in ten still has one after May 17. Planting tender crops after May 7 leaves a 30% risk of a frost on them, after May 11 20%, and after May 17 10%. The 17 days between the even-odds date and the one-in-ten date is narrower than at 54% of the 67 Idaho stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 17 in half of years, as early as October 2 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 11 days later, around October 28; in spring the one-in-ten date for 28°F is May 3, 14 days before the 32°F one. The freeze-free season lasts 168 days in a typical year, longer than at 79% of the 67 Idaho stations; it reaches 190 days one year in ten and falls short of 146 one year in ten. On average 131 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 16 days longer, to about May 16, and return around October 4. Severe cold of 16°F or below comes in 99% of winters, usually between December 3 and February 7.

Spring: the chance of another night this cold after the date
Low	90%	80%	70%	60%	50%	40%	30%	20%	10%
36°F	May 1	May 5	May 8	May 12	May 16	May 19	May 24	May 30	Jun 5
32°F	Apr 17	Apr 22	Apr 26	Apr 29	Apr 30	May 3	May 7	May 11	May 17
28°F	Mar 26	Mar 31	Apr 6	Apr 10	Apr 14	Apr 18	Apr 23	Apr 28	May 3
24°F	Feb 25	Mar 2	Mar 8	Mar 13	Mar 19	Mar 26	Mar 31	Apr 4	Apr 9
20°F	Jan 31	Feb 10	Feb 16	Feb 20	Feb 24	Feb 28	Mar 2	Mar 7	Mar 15
16°F99% of yrs	Jan 3	Jan 13	Jan 24	Feb 1	Feb 7	Feb 12	Feb 17	Feb 23	Feb 28

Fall: the chance the first night this cold has come by the date
Low	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	Sep 20	Sep 26	Sep 29	Oct 2	Oct 4	Oct 6	Oct 10	Oct 13	Oct 18
32°F	Oct 2	Oct 7	Oct 11	Oct 14	Oct 17	Oct 19	Oct 22	Oct 25	Nov 1
28°F	Oct 15	Oct 19	Oct 22	Oct 25	Oct 28	Oct 31	Nov 4	Nov 8	Nov 13
24°F	Oct 24	Oct 29	Nov 2	Nov 7	Nov 10	Nov 13	Nov 17	Nov 21	Nov 26
20°F	Nov 1	Nov 8	Nov 13	Nov 18	Nov 22	Nov 25	Nov 29	Dec 3	Dec 12
16°F99% of yrs	Nov 11	Nov 21	Nov 26	Dec 1	Dec 3	Dec 8	Dec 15	Dec 23	Jan 3

Freeze probabilities 1991–2020 at Emmett 2 E, ID, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.

Frost risk on any date in 83617 →Compare Emmett with another place →

Frost risk through the year in Emmett

Frost curve for Emmett, Idaho (Emmett 2 E, ID, NOAA 1991–2020): the chance of another 32°F night falls from 90% on April 17 to 50% on April 30 and 10% on May 17; the chance that the first fall one has come rises from 10% on October 2 to 50% on October 17 and 90% on November 1. — In Emmett, the spring curve drops under 10% on May 17 and the fall curve passes 10% on October 2, 138 days later; that gap is longer than at 78% of the 67 Idaho stations with frost dates. The spring risk falls from 90% to 10% over 30 days (April 17 to May 17) and the fall risk climbs from 10% to 90% over 30 days (October 2 to November 1): both ends of the season vary about as much. At Boise 7 N, ID, 19 miles southeast, the same gap runs from June 10 to September 27, 29 days shorter.

Chance of a frost after each planting date in Emmett
Planted on	Another 32°F night	28°F night
Apr 16	over 90%	45%
Apr 23	78%	30%
Apr 3050% date	50%	16%
May 7	30%	under 10%
May 14	15%	under 10%
May 21	under 10%	under 10%

Weather by month in Emmett

July is the warmest month at Emmett 2 E, ID, averaging 92°F by day and 58°F at night; January is the coldest at 38°F and 23°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 49% of years.

Warmth for growing adds up to 2,871 growing degree days a year (base 50°F), more than at 81% of the 67 Idaho stations. 29% of them (826) have built up by the end of June, and July adds the most, 764. Precipitation totals 13.4 inches a year, most in December (2.1") and least in August (0.2"); May to September bring 24% of it.

Monthly normals 1991–2020 at Emmett 2 E, ID
Month	High °F	Low °F	Precip. in	32°F night	Nights ≤ 32°F	GDD 50°F
Jan	38	23	1.8	100%	27	0
Feb	46	27	1.3	100%	22	2
Mar	56	32	1.6	100%	17	18
Apr	63	36	1.2	98%	10	74
May	72	44	1.5	49%	2	264
Jun	81	50	0.8	1%	0	469
Jul	92	58	0.3	0%	0	764
Aug	90	57	0.2	0%	0	727
Sep	80	48	0.4	7%	<1	421
Oct	65	38	0.9	88%	6	123
Nov	49	29	1.3	100%	20	8
Dec	39	24	2.1	100%	27	2

Monthly normals 1991–2020 at Emmett 2 E, ID (2,390 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.

Compared with the next station

The nearest other station, Boise 7 N, ID, 19 miles southeast of Emmett and 1,495 feet higher, has a last frost 17 days later (May 17), a first frost 5 days earlier (October 12), a season 21 days shorter.

Frost dates for 83616 (Eagle) →

When it snows in Emmett, Idaho

The first measurable snow (0.1 inch or more) in Emmett usually arrives around December 12, and the last of the season around February 20. Those are the middle dates across the winters of 1991–2020 at Emmett 2 E, ID, 3.3 miles away: half of years saw snow earlier, half later. Snow fell in 67% of those winters. The last 32°F night of spring typically comes 69 days after the last snow.

Planting calendar for 83617

What to do and when, from the 50% frost dates for Emmett, Idaho
When	What to do
February 19 – March 5	Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out.
March 5 – March 19	Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early.
April 2 – April 16	Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil.
April 30 onward	Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast.
by July 25	Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops.
by October 3	Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation.
October 17 onward	Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter.

The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.

Where these figures come from

ZIP 83617 is 3 miles from Emmett 2 E, ID, which stands at 2,390 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 83617 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.

Frost dates across Idaho →

Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.

Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.