USDA Hardiness Zone 5a
Frost Dates for 82301 — Rawlins, Wyoming
NOAA 1991–2020 normals from Rawlins 1N, WY (6,908 ft), 12 miles south.
Updated
In Rawlins, the last spring frost (32°F) is around May 17 in half of years and has passed by May 31 in nine years out of ten. The first fall frost comes around October 2, as early as September 22 one year in ten, leaving a typical freeze-free season of 138 days (NOAA, Rawlins 1N, WY).
- Last spring frost
- May 17
- First fall frost
- October 2
- Growing season
- 138 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 16
- Last snow
- April 29
- Winters with snow
- 97%
- Snow per year
- 49.8"
median, 1991–2020
median, 1991–2020
29 of 30 observed
NOAA normal
Frost risk by date in Rawlins
Half of springs at Rawlins 1N, WY see their last 32°F night by May 17; only one in ten is past it by May 5, and one in ten still has one after May 31. Planting tender crops after May 22 leaves a 30% risk of a frost on them, after May 26 20%, and after May 31 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 58% of the 33 Wyoming stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 2 in half of years, as early as September 22 one year in ten, and holds off past October 17 one year in ten. A hard freeze of 28°F follows 10 days later, around October 12; in spring the one-in-ten date for 28°F is May 18, 13 days before the 32°F one. The freeze-free season lasts 138 days in a typical year, longer than at 73% of the 33 Wyoming stations; it reaches 156 days one year in ten and falls short of 119 one year in ten. On average 177 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 14 days longer, to about May 31, and return around September 24. Severe cold of 16°F or below comes every winter, usually between November 7 and March 31.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 17 | May 22 | May 25 | May 27 | May 31 | Jun 1 | Jun 3 | Jun 5 | Jun 9 |
| 32°F | May 5 | May 9 | May 12 | May 15 | May 17 | May 20 | May 22 | May 26 | May 31 |
| 28°F | Apr 21 | Apr 28 | May 1 | May 3 | May 6 | May 9 | May 11 | May 14 | May 18 |
| 24°F | Apr 6 | Apr 11 | Apr 16 | Apr 21 | Apr 25 | Apr 28 | May 1 | May 4 | May 8 |
| 20°F | Mar 24 | Mar 31 | Apr 3 | Apr 6 | Apr 10 | Apr 14 | Apr 19 | Apr 23 | Apr 30 |
| 16°F | Mar 11 | Mar 17 | Mar 22 | Mar 28 | Mar 31 | Apr 4 | Apr 8 | Apr 13 | Apr 20 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 12 | Sep 15 | Sep 19 | Sep 22 | Sep 24 | Sep 26 | Sep 28 | Oct 1 | Oct 6 |
| 32°F | Sep 22 | Sep 25 | Sep 27 | Sep 30 | Oct 2 | Oct 4 | Oct 8 | Oct 11 | Oct 17 |
| 28°F | Sep 28 | Oct 2 | Oct 5 | Oct 9 | Oct 12 | Oct 15 | Oct 18 | Oct 21 | Oct 25 |
| 24°F | Oct 6 | Oct 10 | Oct 15 | Oct 18 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 4 |
| 20°F | Oct 13 | Oct 18 | Oct 23 | Oct 26 | Oct 29 | Nov 1 | Nov 4 | Nov 9 | Nov 14 |
| 16°F | Oct 21 | Oct 27 | Oct 31 | Nov 3 | Nov 7 | Nov 10 | Nov 14 | Nov 18 | Nov 24 |
Freeze probabilities 1991–2020 at Rawlins 1N, 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 82301 →Compare Rawlins with another place →
Weather by month in Rawlins
July is the warmest month at Rawlins 1N, WY, averaging 82°F by day and 55°F at night; January is the coldest at 31°F and 15°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month.
Warmth for growing adds up to 1,883 growing degree days a year (base 50°F), fewer than at 73% of the 33 Wyoming stations. 25% of them (472) have built up by the end of June, and July adds the most, 571.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 31 | 15 | 100% | 31 | 0 |
| Feb | 33 | 16 | 100% | 27 | 0 |
| Mar | 42 | 24 | 100% | 26 | 2 |
| Apr | 51 | 30 | 100% | 19 | 15 |
| May | 62 | 38 | 95% | 7 | 114 |
| Jun | 74 | 48 | 8% | <1 | 341 |
| Jul | 82 | 55 | 0% | 0 | 571 |
| Aug | 80 | 53 | 0% | 0 | 510 |
| Sep | 71 | 45 | 43% | 2 | 269 |
| Oct | 56 | 34 | 100% | 13 | 57 |
| Nov | 41 | 25 | 100% | 23 | 3 |
| Dec | 31 | 16 | 100% | 29 | 0 |
Monthly normals 1991–2020 at Rawlins 1N, WY (6,908 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 Rawlins, Wyoming
The first measurable snow (0.1 inch or more) in Rawlins usually arrives around October 16, and the last of the season around April 29. Those are the middle dates across the winters of 1991–2020 at Leo 6 SW, WY, 27.3 miles away: half of years saw snow earlier, half later. Snow fell in 97% of those winters. The last 32°F night of spring typically comes 18 days after the last snow.
Planting calendar for 82301
| When | What to do |
|---|---|
| March 8 – March 22 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 22 – April 5 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 19 – May 3 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 17 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 10 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 18 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 2 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 82301 is 12 miles from Rawlins 1N, WY, which stands at 6,908 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 82301 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.