Arvada, Colorado Frost Dates, Growing Season & Hardiness Zone
Frost odds and planting zone for Arvada for the 2027 season, based on 1991–2020 normals.
Last frost date
May 5
typical (50% chance of a later 32°F night)
Safer date: May 18 (10% risk)
earlyMay 5
typicalMay 18
safer
First fall frost
Oct 5
typical (50% chance it has happened by then)
Early-risk date: Sep 20 (10%)
Growing season
151 days
typical frost-free (32°F) season
Short year: 132 days (1 year in 10 is shorter)
USDA hardiness zone
6a
2023 map: -10 to -5°F average coldest night
2012 map: 6a (most of the city)
Where you live in the metro matters. The typical last frost ranges from Apr 30 at Denver Water Dept. to May 8 at Kassler.
By May 5, half of years have seen their last 32°F night. A later freeze, after May 18, happens in 1 year out of 10.
Based on NOAA station Wheat Ridge 2 (USC00058995), 4.4 mi SSE, elevation 5,398 ft (−109 ft vs. city center). Confidence: High.
When is the last frost in Arvada?
In half of years, the last 32°F night has passed by May 5. In 1 year out of 10, one still comes after May 18. The last 36°F night (frost possible on plants) typically comes later, around May 16, and the last 28°F hard freeze earlier, around Apr 25.
The typical date (May 5) and the safer 1-in-10 date (May 18) are 13 days apart. If you plant in between, you're taking a chance; watch the 10-day forecast.
Cold nights don't end with the last freeze. The typical last 36°F night (frost possible on plants in low spots) comes around May 16, 11 days after the typical last 32°F night. On clear, calm nights, frost can form on leaves while the thermometer still reads above freezing.
| Threshold | 10% (safer) | 30% | 50% (typical) | 90% (early) |
|---|---|---|---|---|
| 36°F (frost possible on plants) | May 31 | May 22 | May 16 | May 5 |
| 32°F freeze | May 18 | May 11 | May 5 | Apr 24 |
| 28°F hard freeze | May 9 | May 1 | Apr 25 | Apr 11 |
All probabilities (10–90%)
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F (frost possible on plants) | May 31 | May 27 | May 22 | May 19 | May 16 | May 14 | May 11 | May 8 | May 5 |
| 32°F freeze | May 18 | May 13 | May 11 | May 8 | May 5 | May 3 | May 1 | Apr 28 | Apr 24 |
| 28°F hard freeze | May 9 | May 3 | May 1 | Apr 28 | Apr 25 | Apr 22 | Apr 19 | Apr 16 | Apr 11 |
Is it safe to plant after Mother's Day in Arvada?
Around Arvada, many gardeners use Mother's Day as their cue to plant (CSU PlantTalk). It falls on May 9 in 2027. From then on, the chance of another 32°F night is between 30% and 40%; for a 36°F night (frost possible on plants) it's between 70% and 80% (NOAA 1991–2020, Wheat Ridge 2).
Is it too early to plant in Arvada?
Before May 5 the odds of another 32°F night are better than even; after May 18 they are about 1 in 10 or less.
Today's risk is computed in your browser from the same NOAA probability table, shown as the range between the two nearest NOAA probability levels.
When is the first frost in Arvada?
By Oct 5, half of years have had their first 32°F night. In 1 year out of 10, it comes as early as Sep 20. In a typical year, look for the first 36°F night (frost possible on plants) around Sep 26 and the first 28°F hard freeze around Oct 14.
For fall crops, count back from Oct 5, or from Sep 20 to be safe. Our planting calendar does the math for each crop.
| Threshold | 10% (early) | 30% | 50% (typical) | 90% (late) |
|---|---|---|---|---|
| 36°F (frost possible on plants) | Sep 13 | Sep 20 | Sep 26 | Oct 7 |
| 32°F freeze | Sep 20 | Sep 29 | Oct 5 | Oct 18 |
| 28°F hard freeze | Sep 28 | Oct 8 | Oct 14 | Oct 26 |
All probabilities (10–90%)
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F (frost possible on plants) | Sep 13 | Sep 17 | Sep 20 | Sep 23 | Sep 26 | Sep 29 | Oct 1 | Oct 4 | Oct 7 |
| 32°F freeze | Sep 20 | Sep 25 | Sep 29 | Oct 2 | Oct 5 | Oct 7 | Oct 10 | Oct 12 | Oct 18 |
| 28°F hard freeze | Sep 28 | Oct 4 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 20 | Oct 22 | Oct 26 |
How long is Arvada's growing season?
In a typical year, Arvada gets 151 days between the last and first 32°F nights. About 1 year in 10, the season is shorter than 132 days.
That's enough time for most warm-season vegetables if they go in on time. Long-season crops do best started from transplants.
Each year the station logs an average of 2,681 growing degree days (base 50°F), a measure of the heat available for crop growth.
| Threshold | 10% (long year) | 50% (typical) | 90% (short year) |
|---|---|---|---|
| 36°F (frost possible on plants) | 148 days | 131 days | 112 days |
| 32°F freeze | 167 days | 151 days | 132 days |
| 28°F hard freeze | 191 days | 170 days | 149 days |
How does Arvada's season compare?
At 151 days, the typical frost-free season in Arvada is tied for the 15th longest among the 20 Colorado cities with frost dates on this site.
Nationwide, across the 56 cities with frost dates on this site, the typical frost-free season here outlasts the one in 3 of them and falls short of the one in 50.
Growing degree days (base 50°F)
Annual normal: 2,681 GDD (NOAA flag S, 26 years). Running total by the end of each month (sum of NOAA daily GDD normals, so the year-end total can differ slightly from the annual normal):
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 5 | 27 | 100 | 344 | 850 | 1,547 | 2,179 | 2,554 | 2,662 | 2,680 | 2,681 |
What growing zone is Arvada? (USDA 2023)
The 2023 USDA map puts Arvada in zone 6a (-10 to -5°F average coldest winter night). On the 2012 map, most of the city was 6a. Comparing ZIPs listed in both tables, 1 of 7 moved up half a zone.
| ZIP | 2023 | 2012 | Change | Share of ZIP in Arvada |
|---|---|---|---|---|
| 80002 mostly in city | 6a | 6a | unchanged | 57% |
| 80003 mostly in city | 6a | 6a | unchanged | 81% |
| 80004 mostly in city | 6a | 6a | unchanged | 96% |
| 80005 mostly in city | 6a | 6a | unchanged | 57% |
| 80007 | 6a | 6a | unchanged | 41% |
| 80030 | 6a | 5b | +1 half zone (warmer) | 3% |
| 80033 | 6a | 6a | unchanged | 2% |
Other ZIPs touching Arvada
ZIPs outside the 800 prefix that overlap the city boundary:
- 80221: 2023 6a, 2012 5b (0.2% of the ZIP is in Arvada)
- 80403: 2023 5b, 2012 6a (4.1% of the ZIP is in Arvada)
Zones: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed 2026-10-08. Shown as published in the ZIP tables; this page does not show a zone map. Not the official USDA Plant Hardiness Zone Map (official map: planthardiness.ars.usda.gov).
Does the new zone change Arvada's frost dates?
No. A hardiness zone reflects only the average coldest winter temperature, not the timing of spring or fall frost. Arvada's frost dates come from NOAA's 1991–2020 frost probabilities, and the 2023 zone map didn't change them. Pick perennials that survive winter by zone; time your planting by frost dates.
Why do Arvada frost dates differ between websites?
Some sources list May 11 for Arvada. That's the 30%-risk date: about 3 years in 10 still see a 32°F night after it. We headline the 50% (median) date, May 5.
May 18 is the 10%-risk, or 'safer', date. Only about 1 year in 10 has a 32°F night after it.
You may also see May 16. That's the 50% date for a 36°F night (frost possible on plants) rather than a 32°F freeze, so sites using 36°F as their cutoff list later dates.
Station choice is another reason dates differ. Our 12 qualifying stations within 25 miles of the city center range from Apr 30 to May 8 for the typical (50%) last 32°F frost (table below).
| Date | What it is (NOAA 1991–2020) |
|---|---|
| May 11 | 32°F last frost, 30% risk (a 'balanced' date) |
| May 16 | 36°F last cold night, 50% (frost possible on plants) |
| May 18 | 32°F last frost, 10% risk (the 'safer' date) |
| Apr 25 | 28°F last hard freeze, 50% |
| May 2 | 32°F last frost, 50%, at Northglenn (nearest station with NOAA flag S) |
| Station | Distance | Elevation | Typical last frost |
|---|---|---|---|
| Denver Water Dept. | 10.4 mi SE | 5,228 ft | Apr 30 |
| Northglenn | 8.6 mi ENE | 5,407 ft | May 2 |
| Marston Filter Plant | 15.4 mi SSE | 5,610 ft | May 2 |
| Ralston Reservoir | 4.5 mi W | 5,900 ft | May 3 |
| Lakewood | 6.1 mi SSE | 5,640 ft | May 3 |
| Brighton 3 SE | 18.3 mi ENE | 5,016 ft | May 3 |
| Denver-Stapleton | 15.7 mi ESE | 5,286 ft | May 4 |
| Wheat Ridge 2 used here | 4.4 mi SSE | 5,398 ft | May 5 |
| Denver Centennial Airport | 24.2 mi SE | 5,883 ft | May 5 |
| Boulder | 12.6 mi NNW | 5,484 ft | May 6 |
| Cherry Creek Dam | 22.2 mi SE | 5,647 ft | May 7 |
| Kassler | 23.9 mi S | 5,587 ft | May 8 |
Which weather station is this based on?
- Station
- Wheat Ridge 2 (NOAA USC00058995, COOP)
- Distance
- 4.4 mi SSE of the city center
- Elevation
- 5,398 ft; city center 5,507 ft (USGS), difference −109 ft
- Record
- NOAA completeness flag S, 28 of 30 years (1991–2020)
- Confidence
- High (rule)
Confidence: High. The station is close (4.4 miles from the city center), its elevation differs by just 109 ft, and its frost statistics meet our completeness rule (NOAA flag S, 28 of 30 years).
| Station | ID | Distance | Elev. (Δ) | Last frost 50% | First frost 50% | Season 50% | NOAA flag / years |
|---|---|---|---|---|---|---|---|
| Wheat Ridge 2 | USC00058995 | 4.4 mi SSE | 5,398 ft (-109) | May 5 | Oct 5 | 151 d | S / 28 |
| Ralston Reservoir | USC00056816 | 4.5 mi W | 5,900 ft (+393) | May 3 | Oct 14 | 161 d | R / 22 |
| Lakewood | USC00054762 | 6.1 mi SSE | 5,640 ft (+133) | May 3 | Oct 7 | 155 d | R / 24 |
| Northglenn | USC00055984 | 8.6 mi ENE | 5,407 ft (-100) | May 2 | Oct 11 | 160 d | S / 26 |
| Denver Water Dept. | USC00052223 | 10.4 mi SE | 5,228 ft (-279) | Apr 30 | Oct 12 | 165 d | R / 22 |
| Boulder | USC00050848 | 12.6 mi NNW | 5,484 ft (-23) | May 6 | Oct 5 | 151 d | S / 26 |
| Marston Filter Plant | USC00055402 | 15.4 mi SSE | 5,610 ft (+103) | May 2 | Oct 11 | 160 d | R / 18 |
| Denver-Stapleton | USW00023062 | 15.7 mi ESE | 5,286 ft (-221) | May 4 | Oct 8 | 156 d | S / 28 |
| Brighton 3 SE | USC00050950 | 18.3 mi ENE | 5,016 ft (-491) | May 3 | Oct 7 | 155 d | S / 25 |
| Cherry Creek Dam | USC00051547 | 22.2 mi SE | 5,647 ft (+140) | May 7 | Oct 8 | 152 d | R / 13 |
| Kassler | USC00054452 | 23.9 mi S | 5,587 ft (+80) | May 8 | Oct 3 | 147 d | R / 23 |
| Denver Centennial Airport | USW00093067 | 24.2 mi SE | 5,883 ft (+376) | May 5 | Oct 8 | 154 d | R / 20 |
Other stations within 25 mi (not used)
- Gross Reservoir (USC00053629), 12.8 mi NW, 7,970 ft: typical last frost May 24. Not used: |elev diff| 2463 ft > 500 ft.
- Coal Creek Canyon (USC00051681), 13.2 mi WNW, 8,950 ft: typical last frost Jun 5. Not used: |elev diff| 3443 ft > 500 ft.
- Evergreen (USC00052790), 16.1 mi SSW, 6,985 ft: typical last frost May 23. Not used: |elev diff| 1478 ft > 500 ft.
- Longmont 2 ESE (USC00055116), 23.5 mi N, 4,950 ft: typical last frost May 7. Not used: |elev diff| 557 ft > 500 ft.
101 other NOAA normals stations within 40 km (mostly rain gauges) have no frost statistics.
Arvada planting dates at a glance
Balanced dates use the 30%-risk last-frost date as the anchor. The Arvada planting calendar has typical and safe dates, fall planting and a month-by-month list for 27 vegetables.
| Crop | Start indoors | Plant outdoors (balanced) | Fall |
|---|---|---|---|
| Tomatoes | May 2–16 | Jun 20 | – |
| Peppers | Mar 30 – Apr 13 | May 25 | – |
| Potatoes | – | Apr 27 – May 11 | – |
| Onions (dry, from sets) | – | Apr 13–27 | – |
| Peas | – | Apr 13–27 | sow by Jul 18 |
| Lettuce (leaf) | – | Apr 13–27 | sow by Jul 23 |
| Carrots | – | Apr 27 – May 11 | sow by Jul 13 |
| Beans (snap) | – | May 11 | sow by Jul 9 |
| Summer squash | – | May 11 | sow by Jul 19 |
| Broccoli | Feb 23 – Mar 9 | Apr 13–27 | transplant by Jul 18 |
| Cabbage | Feb 23 – Mar 9 | Apr 13–27 | transplant by Jun 28 |
| Cauliflower | Mar 9–23 | Apr 27 – May 11 | – |
| Kohlrabi | – | Apr 13–27 | sow by Aug 2 |
| Green onions | – | Apr 13–27 | sow by Jul 23 |
| Radishes | – | Apr 13–27 | sow by Aug 22 |
| Spinach | – | Apr 13–27 | sow by Aug 12 |
| Turnips | – | Apr 13–27 | sow by Aug 2 |
| Beets | – | Apr 27 – May 11 | sow by Jul 23 |
| Swiss chard | – | Apr 27 – May 11 | sow by Jul 23 |
| Parsnips | – | Apr 27 – May 11 | – |
| Sweet corn | – | May 11 | – |
| Cucumbers | – | May 11 | sow by Jul 14 |
| Eggplant | Mar 23 – Apr 13 | May 25 | – |
| Cantaloupe | – | May 25 | – |
| Watermelon | – | May 25 | – |
| Winter squash | – | May 25 | – |
| Garlic | – | – | plant Oct 1–14 |
When to plant tomatoes in Arvada · Fall planting dates for Arvada
Frost dates near Arvada
| City | Distance | Last frost | First frost | Season | Zone 2023 |
|---|---|---|---|---|---|
| Lakewood frost dates | 9 mi | May 3 | Oct 7 | 155 days | 6a |
| Denver frost dates | 11 mi | Apr 30 | Oct 12 | 165 days | 6a |
| Thornton frost dates | 13 mi | May 2 | Oct 11 | 160 days | 6a |
| Boulder frost dates | 14 mi | May 6 | Oct 5 | 151 days | 6a |
| Littleton frost dates | 18 mi | May 2 | Oct 11 | 160 days | 5b–6a |
| Commerce City frost dates | 19 mi | May 3 | Oct 7 | 155 days | 5b |
Frequently asked questions
What is the average last frost date in Arvada?
The typical (median, 50%) last 32°F night in Arvada is May 5, based on NOAA 1991–2020 normals at Wheat Ridge 2. For a safer target, use May 18; after that, only about 1 year in 10 still has a freeze.
When is the first frost in Arvada?
Typically by Oct 5 for the first 32°F night, though about 1 year in 10 it comes as early as Sep 20. The first 36°F night (frost possible on plants) typically shows up around Sep 26.
What growing zone is Arvada, Colorado?
Zone 6a. Most of Arvada was 6a on the 2012 map too, but 1 of 7 city ZIPs changed zone.
Is it too early to plant in Arvada?
For frost-tender plants, yes if it's before May 5: until then, the odds of another 32°F night are better than even. Between May 5 and May 18, the risk falls from 50% to 10%. Cool-season crops like peas and lettuce can go in weeks earlier; see the planting calendar.
What temperature is a killing frost?
It depends on the crop. Tender plants such as tomatoes are killed by a light frost, which CSU Extension describes as 28–32°F; below 28°F is a heavy frost. We show NOAA odds for 36°F (frost possible on plants), 32°F (freeze, our headline) and 28°F (hard freeze).
Is first frost the same as first freeze?
Not quite. A 'freeze' means the air reached 32°F. 'Frost' is ice on surfaces, and it can form on calm, clear nights even when the air is a few degrees above freezing. So in Arvada, the first 36°F night (frost possible on plants) typically comes around Sep 26, before the first 32°F night (Oct 5).
Download & sources
- Add Arvada frost & planting dates to your calendar (.ics, 2027)
- Printable planting calendar (PDF)
- How these numbers are calculated
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (annual/seasonal and daily normals, station USC00058995); USDA Plant Hardiness Zone ZIP tables 2023 and 2012 by the PRISM Group, Oregon State University; Census 2020 ZIP/place relationship file; USGS elevation. Long-term odds, not a forecast. Figures and sentences are generated from these data by fixed rules; see the methodology. Last updated 2026-10-08.