USDA Hardiness Zone 5b
Frost Dates for 80134 — Parker, Colorado
NOAA 1991–2020 normals from Parker, CO (5,904 ft), 2 miles east.
Updated
In Parker, the last spring frost (32°F) is around May 9 in half of years and has passed by May 23 in nine years out of ten. The first fall frost comes around October 3, as early as September 21 one year in ten, leaving a typical freeze-free season of 145 days (NOAA, Parker, CO).
- Last spring frost
- May 9
- First fall frost
- October 3
- Growing season
- 145 days
- Hardiness zone
- 5b
50% probability
50% probability
freeze-free, 50%
-15 to -10°F (-26.1 to -23.3°C) coldest night
- First snow
- October 21
- Last snow
- May 2
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
16 of 16 observed
NOAA normal
Frost risk by date in Parker
Half of springs at Parker, CO see their last 32°F night by May 9; only one in ten is past it by April 27, and one in ten still has one after May 23. Planting tender crops after May 14 leaves a 30% risk of a frost on them, after May 18 20%, and after May 23 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 October 3 in half of years, as early as September 21 one year in ten, and holds off past October 15 one year in ten. A hard freeze of 28°F follows 9 days later, around October 12; in spring the one-in-ten date for 28°F is May 12, 11 days before the 32°F one. The freeze-free season lasts 145 days in a typical year, longer than at 54% of the 110 Colorado stations; it reaches 163 days one year in ten and falls short of 127 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 11 days longer, to about May 20, and return around September 25. Severe cold of 16°F or below comes every winter, usually between November 5 and March 26.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 8 | May 11 | May 14 | May 18 | May 20 | May 23 | May 25 | May 29 | Jun 2 |
| 32°F | Apr 27 | May 1 | May 4 | May 6 | May 9 | May 12 | May 14 | May 18 | May 23 |
| 28°F | Apr 15 | Apr 19 | Apr 23 | Apr 27 | Apr 29 | May 2 | May 4 | May 7 | May 12 |
| 24°F | Apr 2 | Apr 7 | Apr 11 | Apr 15 | Apr 19 | Apr 22 | Apr 26 | Apr 30 | May 5 |
| 20°F | Mar 19 | Mar 26 | Mar 31 | Apr 3 | Apr 5 | Apr 9 | Apr 13 | Apr 18 | Apr 23 |
| 16°F | Mar 6 | Mar 12 | Mar 17 | Mar 22 | Mar 26 | Mar 31 | Apr 3 | Apr 8 | Apr 15 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 12 | Sep 18 | Sep 21 | Sep 23 | Sep 25 | Sep 28 | Sep 30 | Oct 2 | Oct 6 |
| 32°F | Sep 21 | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 5 | Oct 7 | Oct 11 | Oct 15 |
| 28°F | Sep 29 | Oct 3 | Oct 6 | Oct 9 | Oct 12 | Oct 15 | Oct 17 | Oct 19 | Oct 23 |
| 24°F | Oct 6 | Oct 12 | Oct 16 | Oct 18 | Oct 20 | Oct 23 | Oct 26 | Oct 29 | Nov 2 |
| 20°F | Oct 15 | Oct 20 | Oct 23 | Oct 26 | Oct 29 | Nov 1 | Nov 4 | Nov 7 | Nov 13 |
| 16°F | Oct 21 | Oct 26 | Oct 30 | Nov 2 | Nov 5 | Nov 9 | Nov 13 | Nov 17 | Nov 23 |
Freeze probabilities 1991–2020 at Parker, 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 80134 →Compare Parker with another place →
Frost risk through the year in Parker
In Parker, the spring curve drops under 10% on May 23 and the fall curve passes 10% on September 21, 121 days later; that gap is longer than at 55% of the 110 Colorado stations with frost dates. The spring risk falls from 90% to 10% over 26 days (April 27 to May 23) and the fall risk climbs from 10% to 90% over 24 days (September 21 to October 15): both ends of the season vary about as much. At Denver Centennial Airport, CO, 6 miles northwest, the same gap runs from May 17 to September 25, 10 days longer.
| Planted on | Another 32°F night | 28°F night |
|---|---|---|
| Apr 25 | over 90% | 65% |
| May 2 | 77% | 40% |
| May 950% date | 50% | 16% |
| May 16 | 25% | under 10% |
| May 23 | under 10% | under 10% |
| May 30 | under 10% | under 10% |
Weather by month in Parker
July is the warmest month at Parker, CO, averaging 88°F by day and 55°F at night; December is the coldest at 47°F and 14°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 82% of years.
Warmth for growing adds up to 2,541 growing degree days a year (base 50°F), more than at 52% of the 110 Colorado stations. 32% of them (810) have built up by the end of June, and July adds the most, 666.
| Month | High °F | Low °F | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|
| Jan | 47 | 15 | 100% | 30 | 1 |
| Feb | 49 | 17 | 100% | 27 | 2 |
| Mar | 57 | 24 | 100% | 26 | 21 |
| Apr | 64 | 31 | 100% | 17 | 68 |
| May | 72 | 40 | 82% | 4 | 223 |
| Jun | 83 | 50 | 2% | <1 | 495 |
| Jul | 88 | 55 | 0% | 0 | 666 |
| Aug | 85 | 54 | 0% | 0 | 601 |
| Sep | 79 | 45 | 38% | 1 | 363 |
| Oct | 67 | 32 | 99% | 15 | 91 |
| Nov | 55 | 22 | 100% | 27 | 10 |
| Dec | 47 | 14 | 100% | 30 | 1 |
Monthly normals 1991–2020 at Parker, CO (5,904 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, Denver Centennial Airport, CO, 6 miles northwest of Parker, has a last frost 4 days earlier (May 5), a first frost 5 days later (October 8), a season 9 days longer.
When it snows in Parker, Colorado
The first measurable snow (0.1 inch or more) in Parker usually arrives around October 21, and the last of the season around May 2. Those are the middle dates across the winters of 1991–2020 at Littleton 7.7 ESE, CO, 6.9 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 80134
| When | What to do |
|---|---|
| February 28 – March 14 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 14 – March 28 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 11 – April 25 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 9 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 11 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 19 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 3 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 80134 is 2 miles from Parker, CO, which stands at 5,904 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 80134 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°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.