USDA Hardiness Zone 6a
Frost Dates for 81323 — Dolores, Colorado
NOAA 1991–2020 normals from Yellow Jacket 4NE, CO (7,090 ft), 12 miles west.
Updated
In Dolores, the last spring frost (32°F) is around May 15 in half of years and has passed by May 31 in nine years out of ten. The first fall frost comes around October 8, as early as September 26 one year in ten, leaving a typical freeze-free season of 147 days (NOAA, Yellow Jacket 4NE, CO).
- Last spring frost
- May 15
- First fall frost
- October 8
- Growing season
- 147 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 4
- Last snow
- May 8
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
16 of 16 observed
NOAA normal
Frost risk by date in Dolores
Half of springs at Yellow Jacket 4NE, CO see their last 32°F night by May 15; only one in ten is past it by April 30, and one in ten still has one after May 31. Planting tender crops after May 20 leaves a 30% risk of a frost on them, after May 24 20%, and after May 31 10%. The 16 days between the even-odds date and the one-in-ten date is wider than at 75% of the 110 Colorado stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 8 in half of years, as early as September 26 one year in ten, and holds off past October 22 one year in ten. A hard freeze of 28°F follows 11 days later, around October 19; in spring the one-in-ten date for 28°F is May 19, 12 days before the 32°F one. The freeze-free season lasts 147 days in a typical year, longer than at 55% of the 110 Colorado stations; it reaches 167 days one year in ten and falls short of 127 one year in ten. On average 160 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 9 days longer, to about May 24, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 20 and March 7.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 13 | May 17 | May 19 | May 21 | May 24 | May 27 | May 30 | Jun 1 | Jun 6 |
| 32°F | Apr 30 | May 4 | May 8 | May 12 | May 15 | May 17 | May 20 | May 24 | May 31 |
| 28°F | Apr 15 | Apr 22 | Apr 25 | Apr 29 | May 2 | May 4 | May 8 | May 12 | May 19 |
| 24°F | Mar 29 | Apr 4 | Apr 8 | Apr 13 | Apr 17 | Apr 21 | Apr 25 | Apr 30 | May 4 |
| 20°F | Mar 5 | Mar 11 | Mar 17 | Mar 24 | Mar 30 | Apr 3 | Apr 7 | Apr 13 | Apr 20 |
| 16°F | Feb 19 | Feb 25 | Feb 28 | Mar 4 | Mar 7 | Mar 11 | Mar 17 | Mar 24 | Mar 31 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 17 | Sep 22 | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 6 | Oct 8 | Oct 13 |
| 32°F | Sep 26 | Oct 1 | Oct 4 | Oct 6 | Oct 8 | Oct 12 | Oct 14 | Oct 17 | Oct 22 |
| 28°F | Oct 4 | Oct 9 | Oct 13 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 29 | Nov 3 |
| 24°F | Oct 13 | Oct 18 | Oct 22 | Oct 26 | Oct 29 | Nov 1 | Nov 4 | Nov 8 | Nov 13 |
| 20°F | Oct 22 | Oct 28 | Nov 2 | Nov 5 | Nov 9 | Nov 13 | Nov 16 | Nov 20 | Nov 25 |
| 16°F | Nov 2 | Nov 8 | Nov 14 | Nov 17 | Nov 20 | Nov 23 | Nov 26 | Nov 30 | Dec 6 |
Freeze probabilities 1991–2020 at Yellow Jacket 4NE, CO, 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 81323 →Compare Dolores with another place →
Weather by month in Dolores
July is the warmest month at Yellow Jacket 4NE, CO, averaging 86°F by day and 55°F at night; January is the coldest at 40°F and 17°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 87% of years.
Warmth for growing adds up to 2,344 growing degree days a year (base 50°F), fewer than at 53% of the 110 Colorado stations. 29% of them (689) have built up by the end of June, and July adds the most, 638.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 40 | 17 | 100% | 30 | 0 |
| Feb | 42 | 19 | 100% | 27 | 0 |
| Mar | 51 | 27 | 100% | 23 | 6 |
| Apr | 60 | 33 | 100% | 14 | 38 |
| May | 69 | 40 | 87% | 4 | 178 |
| Jun | 81 | 50 | 9% | <1 | 467 |
| Jul | 86 | 55 | 0% | 0 | 638 |
| Aug | 83 | 55 | 0% | 0 | 589 |
| Sep | 75 | 47 | 20% | 1 | 349 |
| Oct | 63 | 36 | 98% | 8 | 75 |
| Nov | 51 | 26 | 100% | 23 | 4 |
| Dec | 40 | 18 | 100% | 30 | 0 |
Monthly normals 1991–2020 at Yellow Jacket 4NE, CO (7,090 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, Cortez, CO, 14 miles southwest of Dolores and 923 feet lower, has a last frost 3 days earlier (May 12), a first frost 1 day earlier (October 7).
When it snows in Dolores, Colorado
The first measurable snow (0.1 inch or more) in Dolores usually arrives around November 4, and the last of the season around May 8. Those are the middle dates across the winters of 1991–2020 at Dolores 4.8 ENE, CO, 2.6 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 7 days after the last snow.
Planting calendar for 81323
| When | What to do |
|---|---|
| March 6 – March 20 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 20 – April 3 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 17 – May 1 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 15 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 16 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 24 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 8 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 81323 is 12 miles from Yellow Jacket 4NE, CO, which stands at 7,090 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 81323 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.