USDA Hardiness Zone 5b
Frost Dates for 80401 — Golden, Colorado
NOAA 1991–2020 normals from Lakewood, CO (5,640 ft), 4 miles east.
Updated
In Golden, the last spring frost (32°F) is around May 3 in half of years and has passed by May 18 in nine years out of ten. The first fall frost comes around October 7, as early as September 24 one year in ten, leaving a typical freeze-free season of 155 days (NOAA, Lakewood, CO).
- Last spring frost
- May 3
- First fall frost
- October 7
- Growing season
- 155 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 29
- Last snow
- May 1
- Winters with snow
- 93%
- Snow per year
- 58"
median, 1991–2020
median, 1991–2020
28 of 30 observed
NOAA normal
Frost risk by date in Golden
Half of springs at Lakewood, CO see their last 32°F night by May 3; only one in ten is past it by April 19, and one in ten still has one after May 18. Planting tender crops after May 8 leaves a 30% risk of a frost on them, after May 12 20%, and after May 18 10%. The 15 days between the even-odds date and the one-in-ten date is wider than at 56% of the 110 Colorado stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 7 in half of years, as early as September 24 one year in ten, and holds off past October 21 one year in ten. A hard freeze of 28°F follows 9 days later, around October 16; in spring the one-in-ten date for 28°F is May 7, 11 days before the 32°F one. The freeze-free season lasts 155 days in a typical year, longer than at 70% of the 110 Colorado stations; it reaches 175 days one year in ten and falls short of 133 one year in ten. On average 154 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 14, and return around September 30. Severe cold of 16°F or below comes every winter, usually between November 15 and March 16.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 1 | May 5 | May 9 | May 12 | May 14 | May 17 | May 20 | May 23 | May 29 |
| 32°F | Apr 19 | Apr 24 | Apr 28 | May 1 | May 3 | May 6 | May 8 | May 12 | May 18 |
| 28°F | Apr 5 | Apr 10 | Apr 15 | Apr 19 | Apr 22 | Apr 25 | Apr 29 | May 2 | May 7 |
| 24°F | Mar 23 | Mar 30 | Apr 2 | Apr 5 | Apr 9 | Apr 13 | Apr 17 | Apr 22 | Apr 27 |
| 20°F | Mar 6 | Mar 14 | Mar 20 | Mar 25 | Mar 30 | Apr 2 | Apr 6 | Apr 10 | Apr 19 |
| 16°F | Feb 22 | Feb 28 | Mar 5 | Mar 10 | Mar 16 | Mar 21 | Mar 27 | Mar 31 | Apr 7 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 16 | Sep 21 | Sep 25 | Sep 28 | Sep 30 | Oct 2 | Oct 4 | Oct 7 | Oct 12 |
| 32°F | Sep 24 | Sep 30 | Oct 2 | Oct 4 | Oct 7 | Oct 10 | Oct 13 | Oct 16 | Oct 21 |
| 28°F | Oct 1 | Oct 6 | Oct 9 | Oct 13 | Oct 16 | Oct 18 | Oct 21 | Oct 25 | Oct 30 |
| 24°F | Oct 11 | Oct 16 | Oct 19 | Oct 23 | Oct 26 | Oct 30 | Nov 2 | Nov 6 | Nov 12 |
| 20°F | Oct 18 | Oct 25 | Oct 30 | Nov 2 | Nov 5 | Nov 9 | Nov 13 | Nov 17 | Nov 22 |
| 16°F | Oct 25 | Nov 1 | Nov 6 | Nov 10 | Nov 15 | Nov 19 | Nov 22 | Nov 26 | Nov 30 |
Freeze probabilities 1991–2020 at Lakewood, 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 80401 →Compare Golden with another place →
Frost risk through the year in Golden
In Golden, the spring curve drops under 10% on May 18 and the fall curve passes 10% on September 24, 129 days later; that gap is longer than at 65% of the 110 Colorado stations with frost dates. The spring risk falls from 90% to 10% over 29 days (April 19 to May 18) and the fall risk climbs from 10% to 90% over 27 days (September 24 to October 21): both ends of the season vary about as much. At Wheat Ridge 2, CO, 5 miles northeast, the same gap runs from May 18 to September 20, 4 days shorter.
| Planted on | Another 32°F night | 28°F night |
|---|---|---|
| Apr 19 | over 90% | 60% |
| Apr 26 | 75% | 38% |
| May 350% date | 50% | 18% |
| May 10 | 25% | under 10% |
| May 17 | 12% | under 10% |
| May 24 | under 10% | under 10% |
Weather by month in Golden
July is the warmest month at Lakewood, CO, averaging 86°F by day and 60°F at night; December is the coldest at 45°F and 20°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 60% of years.
Warmth for growing adds up to 2,713 growing degree days a year (base 50°F), more than at 59% of the 110 Colorado stations. 31% of them (839) have built up by the end of June, and July adds the most, 705. Precipitation totals 17.5 inches a year, most in May (2.6") and least in December (0.5"); May to September bring 57% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 45 | 21 | 0.6 | 100% | 29 | 2 |
| Feb | 45 | 22 | 0.8 | 100% | 25 | 3 |
| Mar | 53 | 29 | 1.3 | 100% | 22 | 26 |
| Apr | 59 | 35 | 2.4 | 99% | 13 | 74 |
| May | 68 | 44 | 2.6 | 60% | 3 | 233 |
| Jun | 80 | 54 | 2.1 | 1% | <1 | 501 |
| Jul | 86 | 60 | 2.0 | 0% | 0 | 705 |
| Aug | 84 | 58 | 1.9 | 0% | 0 | 639 |
| Sep | 76 | 49 | 1.4 | 23% | 1 | 385 |
| Oct | 63 | 37 | 1.1 | 99% | 10 | 118 |
| Nov | 52 | 28 | 0.8 | 100% | 22 | 25 |
| Dec | 45 | 20 | 0.5 | 100% | 29 | 3 |
Monthly normals 1991–2020 at Lakewood, CO (5,640 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, Wheat Ridge 2, CO, 5 miles northeast of Golden and 242 feet lower, has a last frost 2 days later (May 5), a first frost 2 days earlier (October 5), a season 4 days shorter.
When it snows in Golden, Colorado
The first measurable snow (0.1 inch or more) in Golden usually arrives around October 29, and the last of the season around May 1. Those are the middle dates across the winters of 1991–2020 at Lakewood, CO, 4 miles away: half of years saw snow earlier, half later. Snow fell in 93% of those winters. The last 32°F night of spring typically comes 2 days after the last snow.
Planting calendar for 80401
| When | What to do |
|---|---|
| February 22 – March 8 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 8 – March 22 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 5 – April 19 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 3 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 15 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 23 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 7 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 80401 is 4 miles from Lakewood, CO, which stands at 5,640 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 80401 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.