Frost dates for ZIP 80421 (Park County, CO)
Average last spring and first fall frost dates with 10%, 50% and 90% odds, from NOAA's 1991–2020 climate normals for the nearest weather station, Bailey, CO (4 miles away).
- Average last spring frostJun 1650% chance of a 32°F freeze after this date
- Average first fall frostSep 850% chance of a 32°F freeze by this date
- Growing season (frost-free)84 daysmedian, 32°F threshold
- USDA hardiness zone5b-15 to -10°F avg. coldest night
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This week in your yard
As of Oct 17, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
41°F Below 50°F
24-hour average · latest 44°F, as of Oct 17, 9:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Boulder 14 W (40 mi).
4-inch depth
42°F Below 50°F
24-hour average · latest 45°F, as of Oct 17, 9:00 PM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Boulder 14 W (40 mi).
Fall: Texas A&M AgriLife times fall pre-emergent (for winter weeds such as annual bluegrass) to soil cooling to about 70°F for several days. The 50–55°F band is the spring trigger. Always read and follow the product label.
7-day forecast and frost risk
The latest National Weather Service 7-day forecast and any Frost Advisory or Freeze Warning for 80421 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 42°F at 4 inches (estimated soil temperature, not a station reading). Fall pre-emergent window is mostly past. Next: spring, when soil reaches 50°F (typically mid-April to mid-May).
Fertilizer window
Lawn region: Mountain West and High Plains. Timing only; always follow the product label.
- Kentucky bluegrass (cool-season): Early fall: Around Labor Day (late August–September); Late fall: Late October–November, before the ground freezes; Late spring: Optional around Memorial Day. Avoid: Early-spring and midsummer feeding (pushes top growth, favors crabgrass).
Plant now
No vegetable planting windows are open this week.
Prune now
No frost-timed pruning windows are open this week.
Spring-flowering shrubs are pruned right after their flowers fade, not by date. See the pruning guide.
Last spring frost odds
| Chance of a 32°F freeze after this date | Date |
|---|---|
| 90% (early: most years still freeze after this) | Jun 2 |
| 50% (the "average" last frost) | Jun 16 |
| 10% (cautious: only 1 year in 10 freezes later) | Jul 1 |
Most gardeners plant frost-tender crops (tomatoes, peppers, basil) after the 50% date, and closer to the 10% date for less risk.
First fall frost odds
| Chance the first 32°F freeze has happened by this date | Date |
|---|---|
| 10% (early: 1 year in 10 freezes this soon) | Aug 27 |
| 50% (the "average" first frost) | Sep 8 |
| 90% (late: most years have frozen by now) | Sep 20 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | n/a | n/a |
| 32°F (freeze) | Jun 16 | Sep 8 |
| 28°F (hard freeze) | May 30 | Sep 19 |
n/a means NOAA did not publish a date at that threshold for this station (usually because it rarely gets that cold).
Vegetable planting calendar for 80421
Dates count from your average last spring frost (Jun 16) and first fall frost (Sep 8). Half of years have a frost after the spring date, so give tender crops (tomatoes, peppers, squash) some slack.
| Crop | Start indoors | Spring planting | Fall planting |
|---|---|---|---|
| Tomato | Apr 21–May 5 | Jun 23–Jul 7 (transplant) | – |
| Pepper (sweet and hot) | Apr 7–21 | Jun 30–Jul 14 (transplant) | – |
| Eggplant | Apr 7–21 | Jun 30–Jul 14 (transplant) | – |
| Tomatillo | Apr 21–May 5 | Jun 23–Jul 7 (transplant) | – |
| Lettuce | Apr 21–May 5 | May 26–Jun 16 (transplant) May 19–Jun 30 (sow outdoors) | Jul 14–Aug 4 (transplant) |
| Spinach | – | May 5–26 (sow outdoors) | Jul 14–Aug 4 (sowing) |
| Kale | Apr 21–May 5 | May 19–Jun 2 (transplant) May 19–Jun 2 (sow outdoors) | Jun 16–Jul 14 (transplant) |
| Collards | Apr 21–May 5 | May 19–Jun 16 (transplant) May 19–Jun 16 (sow outdoors) | – |
| Broccoli | Apr 7–21 | May 19–Jun 2 (transplant) | – |
| Cabbage | Apr 7–21 | May 19–Jun 2 (transplant) | – |
| Cauliflower | Apr 7–21 | Jun 2–16 (transplant) | – |
| Brussels sprouts | Mar 24–Apr 7 | May 19–Jun 2 (transplant) | – |
| Kohlrabi | Apr 21–May 5 | May 19–Jun 2 (transplant) May 19–Jun 2 (sow outdoors) | Jun 30–Jul 14 (sowing) |
| Bok choy / Asian greens | – | May 19–Jun 2 (sow outdoors) | Jul 14–28 (sowing) |
| Arugula | – | May 19–Jun 16 (sow outdoors) | Jul 14–Aug 11 (sowing) |
| Mustard greens | – | May 19–Jun 9 (sow outdoors) | Jul 14–28 (sowing) |
| Swiss chard | May 5–19 | Jun 2–23 (transplant) Jun 2–30 (sow outdoors) | – |
| Beet | – | May 19–Jun 16 (sow outdoors) | Jun 30–Jul 14 (sowing) |
| Carrot | – | May 26–Jun 23 (sow outdoors) | – |
| Radish | – | May 12–Jun 23 (sow outdoors) | Jul 28–Aug 11 (sowing) |
| Turnip | – | May 19–Jun 9 (sow outdoors) | Jun 30–Jul 14 (sowing) |
| Parsnip | – | May 26–Jun 16 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Apr 21–May 19 (sow outdoors) | Jun 16–30 (sowing) |
| Onion (bulbing) | Mar 24–Apr 7 | May 5–19 (transplant) | – |
| Green onion / scallion | – | May 5–Jun 2 (sow outdoors) | Jun 30–Jul 14 (sowing) |
| Leek | Mar 24–Apr 7 | May 19–Jun 2 (transplant) | – |
| Garlic | – | – | Jul 28–Aug 25 (sowing) |
| Shallot | – | May 5–19 (transplant) | Jul 28–Aug 25 (sowing) |
| Potato | – | May 19–Jun 2 (transplant) | – |
| Sweet potato | – | Jul 7–21 (transplant) | – |
| Sweet corn | – | Jun 23–Jul 7 (sow outdoors) | – |
| Bean, bush (snap) | – | Jun 23–Jul 7 (sow outdoors) | – |
| Bean, pole | – | Jun 23–Jul 7 (sow outdoors) | – |
| Lima bean | – | Jun 30–Jul 14 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jul 7–28 (sow outdoors) | – |
| Cucumber | May 19–26 | Jun 23–Jul 7 (transplant) Jun 23–Jul 7 (sow outdoors) | – |
| Summer squash / zucchini | May 19–26 | Jun 23–Jul 7 (transplant) Jun 23–Jul 7 (sow outdoors) | – |
| Winter squash | May 19–26 | Jun 23–Jul 7 (transplant) Jun 23–Jul 7 (sow outdoors) | – |
| Pumpkin | – | Jun 23–Jul 7 (sow outdoors) | – |
| Watermelon | May 19–26 | Jun 30–Jul 14 (transplant) Jun 30–Jul 14 (sow outdoors) | – |
| Cantaloupe / muskmelon | May 19–26 | Jun 30–Jul 14 (transplant) Jun 30–Jul 14 (sow outdoors) | – |
| Okra | May 5–19 | Jun 30–Jul 14 (transplant) Jun 30–Jul 14 (sow outdoors) | – |
| Celery | Mar 24–Apr 7 | Jun 23–30 (transplant) | – |
| Basil | May 5–19 | Jun 23–Jul 7 (transplant) Jun 23–Jul 7 (sow outdoors) | – |
| Cilantro | – | Jun 2–30 (sow outdoors) | Jul 14–28 (sowing) |
| Parsley | Apr 7–21 | Jun 2–16 (transplant) May 26–Jun 16 (sow outdoors) | – |
| Dill | – | Jun 16–30 (sow outdoors) | Jul 14–28 (sowing) |
| Sunflower | – | Jun 16–30 (sow outdoors) | – |
| Asparagus (crowns) | – | May 19–Jun 2 (transplant) | – |
| Rhubarb (crowns) | – | May 19–Jun 2 (transplant) | – |
| Strawberry (plants) | – | May 19–Jun 2 (transplant) | Jun 30–Jul 28 (transplant) |
Typical ranges from university extension planting calendars, adjusted to your frost dates. Probabilities, not guarantees. Fall windows that would overlap spring planting are left out, as are fall crops of frost-tender plants where the frost-free season is under 210 days.
Plants that do well here
Colorado has a university or garden plant program: Plant Select®. Plant frost-tender annuals after June 16 here (the average last frost). Not affiliated with the program.
Where these numbers come from
Station: Bailey, CO (NOAA GHCN-Daily ID USC00050454), elevation 7,752 ft, 4.0 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Grant, CO | 9 mi | Jun 15 | Sep 9 |
| Evergreen, CO | 16 mi | May 23 | Sep 22 |
| Cabin Creek, CO | 17 mi | Jun 6 | Sep 19 |
The average last-frost dates of these stations span 24 days, a rough guide to local variation. See data sources & methods.
Frost questions for 80421
When is the last frost in 80421?
The average (50% chance) last spring freeze of 32°F for ZIP 80421 is June 16. For a more cautious planting date, use July 1, when only 1 year in 10 still sees a later freeze.
When is the first frost in 80421?
The average first fall freeze is September 8. In 1 year in 10 it comes by August 27.
What hardiness zone is 80421?
ZIP 80421 is in USDA zone 5b (-15 to -10°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 80421 right now?
This page shows the latest 2-inch and 4-inch soil temperature from the nearest public soil station (USDA SCAN, NOAA USCRN or TexMesonet), or a labeled estimate when no station is close, against the 50–55°F spring pre-emergent band.
Nearby ZIP codes
80475 80433 Aspen Park 80470 80439 Evergreen 80456 80457 Kittredge 80444 Georgetown 80425
Other ZIP codes in Park County
80420 80432 80440 80448 80449 80456 80475 80820 80827 All Park County frost dates · Colorado frost dates
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