USDA Hardiness Zone 5a
Frost Dates for 83452 — Tetonia, Idaho
NOAA 1991–2020 normals from Tetonia Exp Stn, ID (6,170 ft), 6 miles northwest.
Updated
In Tetonia, the last spring frost (32°F) is around June 15 in half of years and has passed by June 29 in nine years out of ten. The first fall frost comes around September 7, as early as August 24 one year in ten, leaving a typical freeze-free season of 85 days (NOAA, Tetonia Exp Stn, ID).
- Last spring frost
- June 15
- First fall frost
- September 7
- Growing season
- 85 days
- Hardiness zone
- 5a
50% probability
50% probability
freeze-free, 50%
-20 to -15°F (-28.9 to -26.1°C) coldest night
- First snow
- November 2
- Last snow
- April 11
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
22 of 22 observed
NOAA normal
Frost risk by date in Tetonia
Half of springs at Tetonia Exp Stn, ID see their last 32°F night by June 15; only one in ten is past it by May 24, and one in ten still has one after June 29. Planting tender crops after June 21 leaves a 30% risk of a frost on them, after June 24 20%, and after June 29 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 93% of the 67 Idaho stations behind this site's ZIP pages.
In fall the first 32°F night comes by September 7 in half of years, as early as August 24 one year in ten, and holds off past September 23 one year in ten. A hard freeze of 28°F follows 13 days later, around September 20; in spring the one-in-ten date for 28°F is June 14, 15 days before the 32°F one. The freeze-free season lasts 85 days in a typical year, shorter than at 99% of the 67 Idaho stations; it reaches 108 days one year in ten and falls short of 64 one year in ten. On average 218 nights a year drop to 32°F or below. Severe cold of 16°F or below comes every winter, usually between October 25 and April 7.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | May 24 | May 31 | Jun 6 | Jun 11 | Jun 15 | Jun 18 | Jun 21 | Jun 24 | Jun 29 |
| 28°F | May 5 | May 10 | May 14 | May 17 | May 21 | May 25 | May 31 | Jun 6 | Jun 14 |
| 24°F | Apr 21 | Apr 28 | May 1 | May 3 | May 6 | May 9 | May 12 | May 16 | May 22 |
| 20°F | Apr 6 | Apr 11 | Apr 15 | Apr 18 | Apr 22 | Apr 26 | Apr 29 | May 2 | May 8 |
| 16°F | Mar 24 | Mar 30 | Apr 2 | Apr 5 | Apr 7 | Apr 11 | Apr 14 | Apr 18 | Apr 25 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Aug 24 | Aug 30 | Sep 1 | Sep 4 | Sep 7 | Sep 11 | Sep 14 | Sep 18 | Sep 23 |
| 28°F | Sep 3 | Sep 9 | Sep 14 | Sep 17 | Sep 20 | Sep 23 | Sep 26 | Oct 1 | Oct 5 |
| 24°F | Sep 16 | Sep 22 | Sep 26 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 12 | Oct 17 |
| 20°F | Sep 28 | Oct 3 | Oct 6 | Oct 10 | Oct 13 | Oct 16 | Oct 20 | Oct 24 | Oct 30 |
| 16°F | Oct 8 | Oct 14 | Oct 18 | Oct 21 | Oct 25 | Oct 29 | Nov 1 | Nov 6 | Nov 12 |
Freeze probabilities 1991–2020 at Tetonia 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 83452 →Compare Tetonia with another place →
Weather by month in Tetonia
July is the warmest month at Tetonia Exp Stn, ID, averaging 78°F by day and 47°F at night; January is the coldest at 27°F and 8°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 77% of years.
Warmth for growing adds up to 1,187 growing degree days a year (base 50°F), the fewest of the 67 Idaho stations. 21% of them (246) have built up by the end of June, and July adds the most, 393. Precipitation totals 19.1 inches a year, most in May (2.3") and least in July (0.9"); May to September bring 40% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 27 | 8 | 2.0 | 100% | 31 | 0 |
| Feb | 31 | 11 | 1.2 | 100% | 27 | 0 |
| Mar | 39 | 19 | 1.6 | 100% | 29 | 0 |
| Apr | 49 | 27 | 1.8 | 100% | 24 | 6 |
| May | 60 | 35 | 2.3 | 100% | 12 | 64 |
| Jun | 69 | 41 | 1.7 | 77% | 4 | 176 |
| Jul | 78 | 47 | 0.9 | 6% | <1 | 393 |
| Aug | 78 | 45 | 1.2 | 26% | 1 | 369 |
| Sep | 69 | 38 | 1.5 | 96% | 8 | 158 |
| Oct | 54 | 28 | 1.6 | 100% | 23 | 21 |
| Nov | 38 | 19 | 1.2 | 100% | 28 | 1 |
| Dec | 27 | 9 | 2.1 | 100% | 31 | 0 |
Monthly normals 1991–2020 at Tetonia Exp Stn, ID (6,170 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, Driggs, ID, 7 miles southeast of Tetonia, has a last frost 2 days earlier (June 13), a first frost 2 days later (September 9), a season 1 day longer.
When it snows in Tetonia, Idaho
The first measurable snow (0.1 inch or more) in Tetonia usually arrives around November 2, and the last of the season around April 11. Those are the middle dates across the winters of 1991–2020 at Driggs, ID, 6.7 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 65 days after the last snow.
Planting calendar for 83452
| When | What to do |
|---|---|
| April 6 – April 20 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| April 20 – May 4 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| May 18 – June 1 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| June 15 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by June 15 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by August 24 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 7 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 83452 is 6 miles from Tetonia Exp Stn, ID, which stands at 6,170 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 83452 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°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.