Fall in zone 5aPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 80435 (Keystone, 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, Cabin Creek, CO (13 miles away).
- Average last spring frostJun 650% chance of a 32°F freeze after this date
- Average first fall frostSep 1950% chance of a 32°F freeze by this date
- Growing season (frost-free)103 daysmedian, 32°F threshold
- USDA hardiness zone5a-20 to -15°F avg. coldest night
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Frost and freeze alerts from the NWS forecast for 80435, the spring soil-temperature heads-up for pre-emergent, and a short weekly yard-timing email.
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This week in your yard
As of Oct 18, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
42°F Below 50°F
24-hour average · latest 41°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Boulder 14 W (38 mi).
4-inch depth
42°F Below 50°F
24-hour average · latest 42°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Boulder 14 W (38 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 80435 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) | May 25 |
| 50% (the "average" last frost) | Jun 6 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 21 |
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) | Sep 5 |
| 50% (the "average" first frost) | Sep 19 |
| 90% (late: most years have frozen by now) | Sep 30 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Jun 19 | Sep 5 |
| 32°F (freeze) | Jun 6 | Sep 19 |
| 28°F (hard freeze) | May 25 | Sep 26 |
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 80435
Dates count from your average last spring frost (Jun 6) and first fall frost (Sep 19). 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 11–25 | Jun 13–27 (transplant) | – |
| Pepper (sweet and hot) | Mar 28–Apr 11 | Jun 20–Jul 4 (transplant) | – |
| Eggplant | Mar 28–Apr 11 | Jun 20–Jul 4 (transplant) | – |
| Tomatillo | Apr 11–25 | Jun 13–27 (transplant) | – |
| Lettuce | Apr 11–25 | May 16–Jun 6 (transplant) May 9–Jun 20 (sow outdoors) | Jul 25–Aug 15 (transplant) Jul 11–Aug 8 (sowing) |
| Spinach | – | Apr 25–May 16 (sow outdoors) | Jul 25–Aug 15 (sowing) |
| Kale | Apr 11–25 | May 9–23 (transplant) May 9–23 (sow outdoors) | Jun 27–Jul 25 (transplant) Jun 13–Jul 11 (sowing) |
| Collards | Apr 11–25 | May 9–Jun 6 (transplant) May 9–Jun 6 (sow outdoors) | Jun 27–Jul 25 (transplant) Jun 13–Jul 11 (sowing) |
| Broccoli | Mar 28–Apr 11 | May 9–23 (transplant) | Jun 13–Jul 11 (transplant) |
| Cabbage | Mar 28–Apr 11 | May 9–23 (transplant) | Jun 13–Jul 11 (transplant) |
| Cauliflower | Mar 28–Apr 11 | May 23–Jun 6 (transplant) | Jun 13–Jul 11 (transplant) |
| Brussels sprouts | Mar 14–28 | May 9–23 (transplant) | May 30–Jun 20 (transplant) |
| Kohlrabi | Apr 11–25 | May 9–23 (transplant) May 9–23 (sow outdoors) | Jul 11–25 (sowing) |
| Bok choy / Asian greens | – | May 9–23 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Arugula | – | May 9–Jun 6 (sow outdoors) | Jul 25–Aug 22 (sowing) |
| Mustard greens | – | May 9–30 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Swiss chard | Apr 25–May 9 | May 23–Jun 13 (transplant) May 23–Jun 20 (sow outdoors) | Jul 11–25 (sowing) |
| Beet | – | May 9–Jun 6 (sow outdoors) | Jul 11–25 (sowing) |
| Carrot | – | May 16–Jun 13 (sow outdoors) | Jun 27–Jul 11 (sowing) |
| Radish | – | May 2–Jun 13 (sow outdoors) | Aug 8–22 (sowing) |
| Turnip | – | May 9–30 (sow outdoors) | Jul 11–25 (sowing) |
| Parsnip | – | May 16–Jun 6 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Apr 11–May 9 (sow outdoors) | Jun 27–Jul 11 (sowing) |
| Onion (bulbing) | Mar 14–28 | Apr 25–May 9 (transplant) | – |
| Green onion / scallion | – | Apr 25–May 23 (sow outdoors) | Jul 11–25 (sowing) |
| Leek | Mar 14–28 | May 9–23 (transplant) | – |
| Garlic | – | – | Aug 8–Sep 5 (sowing) |
| Shallot | – | Apr 25–May 9 (transplant) | Aug 8–Sep 5 (sowing) |
| Potato | – | May 9–23 (transplant) | May 30–Jun 13 (transplant) |
| Sweet potato | – | Jun 27–Jul 11 (transplant) | – |
| Sweet corn | – | Jun 13–27 (sow outdoors) | – |
| Bean, bush (snap) | – | Jun 13–27 (sow outdoors) | – |
| Bean, pole | – | Jun 13–27 (sow outdoors) | – |
| Lima bean | – | Jun 20–Jul 4 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 27–Jul 18 (sow outdoors) | – |
| Cucumber | May 9–16 | Jun 13–27 (transplant) Jun 13–27 (sow outdoors) | – |
| Summer squash / zucchini | May 9–16 | Jun 13–27 (transplant) Jun 13–27 (sow outdoors) | – |
| Winter squash | May 9–16 | Jun 13–27 (transplant) Jun 13–27 (sow outdoors) | – |
| Pumpkin | – | Jun 13–27 (sow outdoors) | – |
| Watermelon | May 9–16 | Jun 20–Jul 4 (transplant) Jun 20–Jul 4 (sow outdoors) | – |
| Cantaloupe / muskmelon | May 9–16 | Jun 20–Jul 4 (transplant) Jun 20–Jul 4 (sow outdoors) | – |
| Okra | Apr 25–May 9 | Jun 20–Jul 4 (transplant) Jun 20–Jul 4 (sow outdoors) | – |
| Celery | Mar 14–28 | Jun 13–20 (transplant) | – |
| Basil | Apr 25–May 9 | Jun 13–27 (transplant) Jun 13–27 (sow outdoors) | – |
| Cilantro | – | May 23–Jun 20 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Parsley | Mar 28–Apr 11 | May 23–Jun 6 (transplant) May 16–Jun 6 (sow outdoors) | – |
| Dill | – | Jun 6–20 (sow outdoors) | Jul 25–Aug 8 (sowing) |
| Sunflower | – | Jun 6–20 (sow outdoors) | – |
| Asparagus (crowns) | – | May 9–23 (transplant) | – |
| Rhubarb (crowns) | – | May 9–23 (transplant) | – |
| Strawberry (plants) | – | May 9–23 (transplant) | Jul 11–Aug 8 (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 6 here (the average last frost). Not affiliated with the program.
Where these numbers come from
Station: Cabin Creek, CO (NOAA GHCN-Daily ID USC00051186), elevation 10,020 ft, 13.3 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Georgetown, CO | 15 mi | May 30 | Sep 19 |
| Grant, CO | 16 mi | Jun 15 | Sep 9 |
| Vail, CO | 23 mi | Jun 21 | Sep 7 |
The average last-frost dates of these stations span 22 days, a rough guide to local variation. See data sources & methods.
Frost questions for 80435
When is the last frost in 80435?
The average (50% chance) last spring freeze of 32°F for ZIP 80435 is June 6. For a more cautious planting date, use June 21, when only 1 year in 10 still sees a later freeze.
When is the first frost in 80435?
The average first fall freeze is September 19. In 1 year in 10 it comes by September 5.
What hardiness zone is 80435?
ZIP 80435 is in USDA zone 5a (-20 to -15°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 80435 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
80424 Breckenridge 80448 80476 Silver Plume 80444 Georgetown 80443 Copper Mountain 80438 Empire 80420 Alma 81649 Minturn
Other ZIP codes in Summit County
80424 80443 80498 All Summit County frost dates · Colorado frost dates
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Weekly yard timing, plus frost and soil-temperature alerts for your ZIP code.
- Freeze alerts
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Free. One weekly email plus alerts when your ZIP has a frost or a soil-temperature change worth acting on. After you submit, Kit (our email provider) sends a confirmation email: check your email and click the link to confirm. You aren't subscribed until you do. We collect only your email address and ZIP, sent to Kit to deliver The Dial. Unsubscribe anytime.