USDA Hardiness Zone 6b
Frost Dates for 83622 — Garden Valley, Idaho
NOAA 1991–2020 normals from Garden Valley, ID (3,100 ft), 2 miles west.
Updated
In Garden Valley, the last spring frost (32°F) is around June 1 in half of years and has passed by June 20 in nine years out of ten. The first fall frost comes around September 10, as early as August 28 one year in ten, leaving a typical freeze-free season of 102 days (NOAA, Garden Valley, ID).
- Last spring frost
- June 1
- First fall frost
- September 10
- Growing season
- 102 days
- Hardiness zone
- 6b
50% probability
50% probability
freeze-free, 50%
-5 to 0°F (-20.6 to -17.8°C) coldest night
- First snow
- November 14
- Last snow
- March 5
- Winters with snow
- 100%
- Snow per year
- 69.4"
median, 1991–2020
median, 1991–2020
19 of 19 observed
NOAA normal
Frost risk by date in Garden Valley
Half of springs at Garden Valley, ID see their last 32°F night by June 1; only one in ten is past it by May 13, and one in ten still has one after June 20. Planting tender crops after June 10 leaves a 30% risk of a frost on them, after June 14 20%, and after June 20 10%. The 19 days between the even-odds date and the one-in-ten date is wider than at 60% of the 67 Idaho stations behind this site's ZIP pages.
In fall the first 32°F night comes by September 10 in half of years, as early as August 28 one year in ten, and holds off past September 27 one year in ten. A hard freeze of 28°F follows 14 days later, around September 24; in spring the one-in-ten date for 28°F is May 30, 21 days before the 32°F one. The freeze-free season lasts 102 days in a typical year, shorter than at 93% of the 67 Idaho stations; it reaches 125 days one year in ten and falls short of 76 one year in ten. On average 180 nights a year drop to 32°F or below. Severe cold of 16°F or below comes every winter, usually between November 10 and March 4.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | May 13 | May 18 | May 23 | May 27 | Jun 1 | Jun 6 | Jun 10 | Jun 14 | Jun 20 |
| 28°F | Apr 26 | May 1 | May 4 | May 7 | May 11 | May 14 | May 17 | May 22 | May 30 |
| 24°F | Mar 29 | Apr 4 | Apr 11 | Apr 17 | Apr 22 | Apr 26 | Apr 30 | May 4 | May 11 |
| 20°F | Mar 4 | Mar 9 | Mar 13 | Mar 17 | Mar 22 | Mar 29 | Apr 1 | Apr 9 | Apr 18 |
| 16°F | Feb 18 | Feb 24 | Feb 28 | Mar 2 | Mar 4 | Mar 6 | Mar 10 | Mar 14 | Mar 19 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Aug 28 | Sep 1 | Sep 4 | Sep 6 | Sep 10 | Sep 13 | Sep 17 | Sep 20 | Sep 27 |
| 28°F | Sep 8 | Sep 14 | Sep 18 | Sep 21 | Sep 24 | Sep 28 | Oct 1 | Oct 4 | Oct 10 |
| 24°F | Sep 22 | Sep 28 | Oct 1 | Oct 4 | Oct 8 | Oct 12 | Oct 17 | Oct 22 | Oct 29 |
| 20°F | Oct 4 | Oct 10 | Oct 16 | Oct 21 | Oct 26 | Oct 31 | Nov 3 | Nov 8 | Nov 18 |
| 16°F | Oct 20 | Oct 27 | Nov 1 | Nov 5 | Nov 10 | Nov 15 | Nov 21 | Nov 26 | Dec 2 |
Freeze probabilities 1991–2020 at Garden Valley, 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 83622 →Compare Garden Valley with another place →
Weather by month in Garden Valley
July is the warmest month at Garden Valley, ID, averaging 89°F by day and 48°F at night; January is the coldest at 34°F and 19°F. A freezing night is all but certain in every month from September to May (a 90% chance or more). July is the only month with under a 10% chance of a 32°F night. In spring, June still brings one in 50% of years.
Warmth for growing adds up to 1,953 growing degree days a year (base 50°F), fewer than at 66% of the 67 Idaho stations. 27% of them (518) have built up by the end of June, and July adds the most, 569. Precipitation totals 26.6 inches a year, most in December (5.0") and least in July (0.4"); May to September bring 19% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 34 | 19 | 4.2 | 100% | 30 | 0 |
| Feb | 41 | 22 | 2.5 | 100% | 26 | 0 |
| Mar | 52 | 27 | 2.9 | 100% | 24 | 2 |
| Apr | 60 | 32 | 2.1 | 100% | 16 | 32 |
| May | 69 | 38 | 1.8 | 99% | 6 | 157 |
| Jun | 78 | 44 | 1.4 | 50% | 1 | 328 |
| Jul | 89 | 48 | 0.4 | 2% | 0 | 569 |
| Aug | 89 | 46 | 0.5 | 20% | <1 | 532 |
| Sep | 79 | 39 | 0.9 | 92% | 6 | 277 |
| Oct | 64 | 31 | 1.7 | 100% | 18 | 57 |
| Nov | 44 | 26 | 3.2 | 100% | 23 | 1 |
| Dec | 33 | 20 | 5.0 | 100% | 29 | 0 |
Monthly normals 1991–2020 at Garden Valley, ID (3,100 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, 28 miles southwest of Garden Valley and 785 feet higher, has a last frost 15 days earlier (May 17), a first frost 32 days later (October 12), a season 45 days longer.
When it snows in Garden Valley, Idaho
The first measurable snow (0.1 inch or more) in Garden Valley usually arrives around November 14, and the last of the season around March 5. Those are the middle dates across the winters of 1991–2020 at Garden Valley, ID, 1.7 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 88 days after the last snow.
Planting calendar for 83622
| When | What to do |
|---|---|
| March 23 – April 6 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| April 6 – April 20 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| May 4 – May 18 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| June 1 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by June 18 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by August 27 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 10 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 83622 is 2 miles from Garden Valley, ID, which stands at 3,100 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 83622 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°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.