USDA Hardiness Zone 5a
Frost Dates for 81144 — Monte Vista, Colorado
NOAA 1991–2020 normals from Monte Vista 2W, CO (7,695 ft), 2 miles west.
Updated
In Monte Vista, the last spring frost (32°F) is around June 11 in half of years and has passed by June 25 in nine years out of ten. The first fall frost comes around September 13, as early as September 1 one year in ten, leaving a typical freeze-free season of 92 days (NOAA, Monte Vista 2W, CO).
- Last spring frost
- June 11
- First fall frost
- September 13
- Growing season
- 92 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 24
- Winters with snow
- 100%
- Snow per year
- 35.4"
median, 1991–2020
median, 1991–2020
27 of 27 observed
NOAA normal
Frost risk by date in Monte Vista
Half of springs at Monte Vista 2W, CO see their last 32°F night by June 11; only one in ten is past it by June 1, and one in ten still has one after June 25. Planting tender crops after June 17 leaves a 30% risk of a frost on them, after June 20 20%, and after June 25 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 45% of the 110 Colorado stations behind this site's ZIP pages.
In fall the first 32°F night comes by September 13 in half of years, as early as September 1 one year in ten, and holds off past September 24 one year in ten. A hard freeze of 28°F follows 10 days later, around September 23; in spring the one-in-ten date for 28°F is June 12, 13 days before the 32°F one. The freeze-free season lasts 92 days in a typical year, shorter than at 88% of the 110 Colorado stations; it reaches 108 days one year in ten and falls short of 74 one year in ten. On average 229 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 21.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Jun 1 | Jun 4 | Jun 6 | Jun 9 | Jun 11 | Jun 14 | Jun 17 | Jun 20 | Jun 25 |
| 28°F | May 15 | May 19 | May 23 | May 27 | May 30 | Jun 1 | Jun 4 | Jun 7 | Jun 12 |
| 24°F | May 1 | May 5 | May 8 | May 11 | May 15 | May 17 | May 20 | May 23 | May 29 |
| 20°F | Apr 19 | Apr 23 | Apr 27 | Apr 30 | May 1 | May 4 | May 6 | May 10 | May 15 |
| 16°F | Apr 8 | Apr 13 | Apr 16 | Apr 19 | Apr 21 | Apr 24 | Apr 27 | Apr 30 | May 4 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | too rare for a date | ||||||||
| 32°F | Sep 1 | Sep 5 | Sep 7 | Sep 11 | Sep 13 | Sep 15 | Sep 17 | Sep 20 | Sep 24 |
| 28°F | Sep 11 | Sep 15 | Sep 18 | Sep 21 | Sep 23 | Sep 26 | Sep 28 | Oct 1 | Oct 4 |
| 24°F | Sep 19 | Sep 23 | Sep 26 | Sep 28 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 12 |
| 20°F | Sep 27 | Oct 1 | Oct 4 | Oct 6 | Oct 9 | Oct 11 | Oct 14 | Oct 18 | Oct 22 |
| 16°F | Oct 3 | Oct 8 | Oct 11 | Oct 15 | Oct 18 | Oct 20 | Oct 23 | Oct 27 | Nov 1 |
Freeze probabilities 1991–2020 at Monte Vista 2W, 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 81144 →Compare Monte Vista with another place →
Weather by month in Monte Vista
July is the warmest month at Monte Vista 2W, CO, averaging 80°F by day and 45°F at night; January is the coldest at 33°F and -2°F. A freezing night is all but certain in every month from September to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 90% of years.
Warmth for growing adds up to 1,170 growing degree days a year (base 50°F), fewer than at 86% of the 110 Colorado stations. 27% of them (313) have built up by the end of June, and July adds the most, 387. Precipitation totals 9.2 inches a year, most in August (1.6") and least in February (0.3"); May to September bring 60% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 33 | -2 | 0.4 | 100% | 31 | 0 |
| Feb | 40 | 5 | 0.3 | 100% | 28 | 0 |
| Mar | 52 | 16 | 0.7 | 100% | 31 | 0 |
| Apr | 59 | 22 | 0.7 | 100% | 28 | 5 |
| May | 67 | 31 | 0.8 | 100% | 14 | 70 |
| Jun | 77 | 38 | 0.5 | 90% | 2 | 238 |
| Jul | 80 | 45 | 1.5 | 5% | 0 | 387 |
| Aug | 78 | 43 | 1.6 | 9% | <1 | 327 |
| Sep | 73 | 35 | 1.1 | 98% | 7 | 135 |
| Oct | 62 | 23 | 0.8 | 100% | 27 | 9 |
| Nov | 48 | 12 | 0.4 | 100% | 30 | 0 |
| Dec | 35 | 0 | 0.4 | 100% | 31 | 0 |
Monthly normals 1991–2020 at Monte Vista 2W, CO (7,695 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, Center 4 SSW, CO, 9 miles north of Monte Vista, has a last frost 18 days earlier (May 24), a first frost 11 days later (September 24), a season 28 days longer.
When it snows in Monte Vista, Colorado
The first measurable snow (0.1 inch or more) in Monte Vista usually arrives around November 2, and the last of the season around April 24. Those are the middle dates across the winters of 1991–2020 at Monte Vista 2W, CO, 2.2 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 48 days after the last snow.
Planting calendar for 81144
| When | What to do |
|---|---|
| April 2 – April 16 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| April 16 – April 30 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| May 14 – May 28 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| June 11 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by June 21 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by August 30 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| September 13 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 81144 is 2 miles from Monte Vista 2W, CO, which stands at 7,695 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 81144 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.