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USDA Hardiness Zone 5b

Frost Dates for 83210 — Aberdeen, Idaho

NOAA 1991–2020 normals from Aberdeen Exp Stn, ID (4,405 ft), 1 miles south.

Updated

In Aberdeen, the last spring frost (32°F) is around May 21 in half of years and has passed by June 13 in nine years out of ten. The first fall frost comes around September 20, as early as September 2 one year in ten, leaving a typical freeze-free season of 118 days (NOAA, Aberdeen Exp Stn, ID).

Last spring frost
May 21

50% probability

First fall frost
September 20

50% probability

Growing season
118 days

freeze-free, 50%

Hardiness zone
5b

-15 to -10°F (-26.1 to -23.3°C) coldest night

First snow
November 25

median, 1991–2020

Last snow
March 18

median, 1991–2020

Winters with snow
100%

30 of 30 observed

Snow per year
25.2"

NOAA normal

Frost risk by date in Aberdeen

Half of springs at Aberdeen Exp Stn, ID see their last 32°F night by May 21; only one in ten is past it by May 4, and one in ten still has one after June 13. Planting tender crops after May 31 leaves a 30% risk of a frost on them, after June 5 20%, and after June 13 10%. The 23 days between the even-odds date and the one-in-ten date is wider than at 87% of the 67 Idaho stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.

In fall the first 32°F night comes by September 20 in half of years, as early as September 2 one year in ten, and holds off past October 4 one year in ten. A hard freeze of 28°F follows 11 days later, around October 1; in spring the one-in-ten date for 28°F is May 17, 27 days before the 32°F one. The freeze-free season lasts 118 days in a typical year, shorter than at 82% of the 67 Idaho stations; it reaches 141 days one year in ten and falls short of 91 one year in ten. On average 196 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 22 days longer, to about June 12, and return around September 5. Severe cold of 16°F or below comes every winter, usually between November 6 and March 13.

Spring: the chance of another night this cold after the date
Low90%80%70%60%50%40%30%20%10%
36°FMay 23May 31Jun 4Jun 9Jun 12Jun 16Jun 19Jun 23Jun 28
32°FMay 4May 9May 13May 16May 21May 26May 31Jun 5Jun 13
28°FApr 20Apr 26Apr 28Apr 30May 3May 5May 8May 12May 17
24°FApr 6Apr 11Apr 15Apr 18Apr 21Apr 24Apr 27Apr 30May 5
20°FMar 14Mar 23Mar 31Apr 4Apr 7Apr 12Apr 16Apr 20Apr 25
16°FFeb 27Mar 4Mar 7Mar 10Mar 13Mar 18Mar 30Apr 4Apr 10
Fall: the chance the first night this cold has come by the date
Low10%20%30%40%50%60%70%80%90%
36°FAug 21Aug 27Aug 31Sep 3Sep 5Sep 9Sep 13Sep 17Sep 22
32°FSep 2Sep 8Sep 13Sep 17Sep 20Sep 22Sep 26Sep 29Oct 4
28°FSep 15Sep 20Sep 24Sep 28Oct 1Oct 4Oct 7Oct 12Oct 17
24°FSep 27Oct 3Oct 6Oct 11Oct 14Oct 17Oct 21Oct 24Oct 31
20°FOct 11Oct 17Oct 21Oct 25Oct 28Oct 31Nov 2Nov 6Nov 13
16°FOct 22Oct 27Nov 1Nov 2Nov 6Nov 10Nov 15Nov 20Nov 25

Freeze probabilities 1991–2020 at Aberdeen Exp Stn, 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 83210 →Compare Aberdeen with another place →

Weather by month in Aberdeen

July is the warmest month at Aberdeen Exp Stn, ID, averaging 87°F by day and 51°F at night; January is the coldest at 32°F and 14°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 29% of years.

Warmth for growing adds up to 2,006 growing degree days a year (base 50°F), fewer than at 61% of the 67 Idaho stations. 27% of them (542) have built up by the end of June, and July adds the most, 592. Precipitation totals 9.7 inches a year, most in May (1.2") and least in July (0.4"); May to September bring 39% of it.

Monthly normals 1991–2020 at Aberdeen Exp Stn, ID
MonthHigh °FLow °FPrecip. in32°F nightNights ≤ 32°FGDD 50°F
Jan32140.9100%310
Feb37170.6100%270
Mar48260.9100%282
Apr58310.9100%2027
May68401.294%6165
Jun77461.029%1347
Jul87510.40%0592
Aug87490.47%<1551
Sep76400.881%5271
Oct61300.9100%2149
Nov45220.7100%272
Dec33151.0100%300

Monthly normals 1991–2020 at Aberdeen Exp Stn, ID (4,405 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, American Falls, ID, 12 miles south of Aberdeen, has a last frost 17 days earlier (May 4), a first frost 18 days later (October 8), a season 37 days longer.

Frost dates for 83211 (American Falls) →

When it snows in Aberdeen, Idaho

The first measurable snow (0.1 inch or more) in Aberdeen usually arrives around November 25, and the last of the season around March 18. Those are the middle dates across the winters of 1991–2020 at Aberdeen Exp Stn, ID, 1.3 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 64 days after the last snow.

Planting calendar for 83210

What to do and when, from the 50% frost dates for Aberdeen, Idaho
WhenWhat to do
March 12 – March 26Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out.
March 26 – April 9Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early.
April 23 – May 7Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil.
May 21 onwardTransplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast.
by June 28Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops.
by September 6Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation.
September 20 onwardPlant 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 83210 is 1 mile from Aberdeen Exp Stn, ID, which stands at 4,405 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 83210 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°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.

Other zone 5b places in Idaho