USDA Hardiness Zone 5a
Frost Dates for 83101 — Kemmerer, Wyoming
NOAA 1991–2020 normals from La Barge, WY (6,598 ft), 28 miles northeast.
Updated
In Kemmerer, the last spring frost (32°F) is around June 9 in half of years and has passed by June 27 in nine years out of ten. The first fall frost comes around September 4, as early as August 21 one year in ten, leaving a typical freeze-free season of 84 days (NOAA, La Barge, WY).
- Last spring frost
- June 9
- First fall frost
- September 4
- Growing season
- 84 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
- October 30
- Last snow
- April 25
- Winters with snow
- 100%
- Snow per year
- 49.7"
median, 1991–2020
median, 1991–2020
25 of 25 observed
NOAA normal
Frost risk by date in Kemmerer
Half of springs at La Barge, WY see their last 32°F night by June 9; only one in ten is past it by May 24, and one in ten still has one after June 27. Planting tender crops after June 16 leaves a 30% risk of a frost on them, after June 21 20%, and after June 27 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 85% of the 33 Wyoming stations behind this site's ZIP pages.
In fall the first 32°F night comes by September 4 in half of years, as early as August 21 one year in ten, and holds off past September 18 one year in ten. A hard freeze of 28°F follows 11 days later, around September 15; in spring the one-in-ten date for 28°F is June 11, 16 days before the 32°F one. The freeze-free season lasts 84 days in a typical year, shorter than at 88% of the 33 Wyoming stations; it reaches 105 days one year in ten and falls short of 62 one year in ten. On average 240 nights a year drop to 32°F or below. Severe cold of 16°F or below comes every winter, usually between October 18 and April 16.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | May 24 | May 31 | Jun 2 | Jun 6 | Jun 9 | Jun 13 | Jun 16 | Jun 21 | Jun 27 |
| 28°F | May 9 | May 14 | May 17 | May 20 | May 24 | May 28 | May 31 | Jun 5 | Jun 11 |
| 24°F | Apr 29 | May 2 | May 6 | May 8 | May 10 | May 13 | May 16 | May 20 | May 28 |
| 20°F | Apr 16 | Apr 21 | Apr 24 | Apr 28 | Apr 30 | May 3 | May 5 | May 9 | May 14 |
| 16°F | Mar 31 | Apr 4 | Apr 8 | Apr 12 | Apr 16 | Apr 19 | Apr 23 | Apr 28 | May 2 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Aug 21 | Aug 26 | Aug 30 | Sep 1 | Sep 4 | Sep 7 | Sep 10 | Sep 13 | Sep 18 |
| 28°F | Sep 1 | Sep 5 | Sep 9 | Sep 12 | Sep 15 | Sep 19 | Sep 22 | Sep 26 | Sep 30 |
| 24°F | Sep 11 | Sep 16 | Sep 20 | Sep 23 | Sep 26 | Sep 29 | Oct 1 | Oct 4 | Oct 9 |
| 20°F | Sep 22 | Sep 28 | Oct 1 | Oct 4 | Oct 7 | Oct 11 | Oct 14 | Oct 17 | Oct 20 |
| 16°F | Oct 1 | Oct 6 | Oct 11 | Oct 15 | Oct 18 | Oct 20 | Oct 23 | Oct 25 | Oct 29 |
Freeze probabilities 1991–2020 at La Barge, WY, 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 83101 →Compare Kemmerer with another place →
Weather by month in Kemmerer
July is the warmest month at La Barge, WY, averaging 83°F by day and 46°F at night; January is the coldest at 30°F and -2°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 75% of years.
Warmth for growing adds up to 1,305 growing degree days a year (base 50°F), fewer than at 88% of the 33 Wyoming stations. 23% of them (305) have built up by the end of June, and July adds the most, 457. Precipitation totals 8.8 inches a year, most in May (1.3") and least in November (0.3"); May to September bring 58% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 30 | -2 | 0.4 | 100% | 31 | 0 |
| Feb | 33 | 2 | 0.4 | 100% | 28 | 0 |
| Mar | 45 | 17 | 0.5 | 100% | 31 | 0 |
| Apr | 54 | 24 | 0.7 | 100% | 28 | 6 |
| May | 64 | 33 | 1.3 | 100% | 15 | 68 |
| Jun | 74 | 40 | 1.0 | 75% | 4 | 232 |
| Jul | 83 | 46 | 0.9 | 6% | 1 | 457 |
| Aug | 82 | 44 | 0.9 | 34% | 1 | 395 |
| Sep | 72 | 34 | 1.0 | 100% | 14 | 137 |
| Oct | 58 | 24 | 0.9 | 100% | 27 | 10 |
| Nov | 42 | 11 | 0.3 | 100% | 30 | 0 |
| Dec | 30 | 0 | 0.5 | 100% | 31 | 0 |
Monthly normals 1991–2020 at La Barge, WY (6,598 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
When it snows in Kemmerer, Wyoming
The first measurable snow (0.1 inch or more) in Kemmerer usually arrives around October 30, and the last of the season around April 25. Those are the middle dates across the winters of 1991–2020 at Kemmerer 2N, WY, 8.2 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 45 days after the last snow.
Planting calendar for 83101
| When | What to do |
|---|---|
| March 31 – April 14 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| April 14 – April 28 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| May 12 – May 26 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| June 9 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by June 12 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by August 21 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 4 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 83101 is 28 miles from La Barge, WY, which stands at 6,598 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. That is farther than 25 miles, so local frost can differ noticeably from these figures. 1 other ZIP code shares the station; its figures are presented in full for 83113 (Big Piney). The 2023 USDA Plant Hardiness Zone Map lists ZIP 83101 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.