USDA Hardiness Zone 6a
Frost Dates for 83856 — Priest River, Idaho
NOAA 1991–2020 normals from Priest Rvr Exp Stn, ID (2,371 ft), 4 miles northeast.
Updated
In Priest River, the last spring frost (32°F) is around May 20 in half of years and has passed by June 4 in nine years out of ten. The first fall frost comes around September 13, as early as September 1 one year in ten, leaving a typical freeze-free season of 114 days (NOAA, Priest Rvr Exp Stn, ID).
- Last spring frost
- May 20
- First fall frost
- September 13
- Growing season
- 114 days
- Hardiness zone
- 6a
50% probability
50% probability
freeze-free, 50%
-10 to -5°F (-23.3 to -20.6°C) coldest night
- First snow
- November 15
- Last snow
- March 20
- Winters with snow
- 100%
- Snow per year
- 73.9"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Priest River
Half of springs at Priest Rvr Exp Stn, ID see their last 32°F night by May 20; only one in ten is past it by May 6, and one in ten still has one after June 4. Planting tender crops after May 27 leaves a 30% risk of a frost on them, after May 30 20%, and after June 4 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 78% of the 67 Idaho stations behind this site's ZIP pages.
In fall the first 32°F night comes by September 13 in half of years, as early as September 1 one year in ten, and holds off past September 30 one year in ten. A hard freeze of 28°F follows 15 days later, around September 28; in spring the one-in-ten date for 28°F is May 17, 18 days before the 32°F one. The freeze-free season lasts 114 days in a typical year, shorter than at 85% of the 67 Idaho stations; it reaches 137 days one year in ten and falls short of 92 one year in ten. On average 190 nights a year drop to 32°F or below. Severe cold of 16°F or below comes every winter, usually between November 14 and March 8.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | May 6 | May 11 | May 14 | May 17 | May 20 | May 24 | May 27 | May 30 | Jun 4 |
| 28°F | Apr 19 | Apr 25 | Apr 29 | Apr 30 | May 4 | May 7 | May 10 | May 13 | May 17 |
| 24°F | Mar 26 | Mar 31 | Apr 4 | Apr 9 | Apr 13 | Apr 18 | Apr 23 | Apr 27 | May 3 |
| 20°F | Mar 5 | Mar 10 | Mar 14 | Mar 18 | Mar 22 | Mar 27 | Mar 31 | Apr 4 | Apr 13 |
| 16°F | Feb 21 | Feb 28 | Mar 2 | Mar 5 | Mar 8 | Mar 10 | Mar 14 | Mar 18 | Mar 23 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Sep 1 | Sep 3 | Sep 7 | Sep 9 | Sep 13 | Sep 16 | Sep 19 | Sep 23 | Sep 30 |
| 28°F | Sep 12 | Sep 17 | Sep 21 | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 7 | Oct 13 |
| 24°F | Sep 26 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 15 | Oct 19 | Oct 25 | Nov 1 |
| 20°F | Oct 6 | Oct 13 | Oct 20 | Oct 25 | Oct 29 | Nov 2 | Nov 7 | Nov 14 | Nov 21 |
| 16°F | Oct 21 | Oct 29 | Nov 4 | Nov 9 | Nov 14 | Nov 18 | Nov 24 | Nov 30 | Dec 8 |
Freeze probabilities 1991–2020 at Priest Rvr 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 83856 →Compare Priest River with another place →
Weather by month in Priest River
July is the warmest month at Priest Rvr Exp Stn, ID, averaging 83°F by day and 48°F at night; December is the coldest at 31°F and 22°F. A freezing night is all but certain in every month from September 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 15% of years.
Warmth for growing adds up to 1,559 growing degree days a year (base 50°F), fewer than at 88% of the 67 Idaho stations. 28% of them (432) have built up by the end of June, and July adds the most, 477. Precipitation totals 32.7 inches a year, most in December (4.5") and least in August (0.9"); May to September bring 26% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 32 | 22 | 4.0 | 100% | 31 | 0 |
| Feb | 37 | 22 | 2.6 | 100% | 27 | 0 |
| Mar | 46 | 26 | 3.4 | 100% | 28 | 0 |
| Apr | 57 | 31 | 2.5 | 100% | 20 | 17 |
| May | 68 | 39 | 2.8 | 96% | 7 | 145 |
| Jun | 74 | 44 | 2.6 | 15% | <1 | 270 |
| Jul | 83 | 48 | 1.0 | 2% | 0 | 477 |
| Aug | 83 | 46 | 0.9 | 9% | <1 | 445 |
| Sep | 72 | 39 | 1.3 | 90% | 6 | 187 |
| Oct | 54 | 32 | 2.9 | 100% | 17 | 17 |
| Nov | 38 | 27 | 4.2 | 100% | 24 | 0 |
| Dec | 31 | 22 | 4.5 | 100% | 31 | 0 |
Monthly normals 1991–2020 at Priest Rvr Exp Stn, ID (2,371 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, Newport, WA, 11 miles southwest of Priest River and 209 feet lower, has a last frost 8 days earlier (May 12), a first frost 8 days later (September 21), a season 16 days longer.
When it snows in Priest River, Idaho
The first measurable snow (0.1 inch or more) in Priest River usually arrives around November 15, and the last of the season around March 20. Those are the middle dates across the winters of 1991–2020 at Priest Rvr Exp Stn, ID, 4.2 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 61 days after the last snow.
Planting calendar for 83856
| When | What to do |
|---|---|
| March 11 – March 25 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 25 – April 8 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 22 – May 6 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 20 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by June 21 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by August 30 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 13 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 83856 is 4 miles from Priest Rvr Exp Stn, ID, which stands at 2,371 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 83856 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.
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.