Fall in zone 5bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 80451 (Hot Sulphur Springs, 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, Williams Fork Dam, CO (8 miles away).
- Average last spring frostJun 1250% chance of a 32°F freeze after this date
- Average first fall frostSep 1050% chance of a 32°F freeze by this date
- Growing season (frost-free)89 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 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 (27 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 (27 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 80451 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 31 |
| 50% (the "average" last frost) | Jun 12 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 25 |
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 31 |
| 50% (the "average" first frost) | Sep 10 |
| 90% (late: most years have frozen by now) | Sep 21 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Jun 28 | Aug 29 |
| 32°F (freeze) | Jun 12 | Sep 10 |
| 28°F (hard freeze) | May 26 | Sep 20 |
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 80451
Dates count from your average last spring frost (Jun 12) and first fall frost (Sep 10). 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 17–May 1 | Jun 19–Jul 3 (transplant) | – |
| Pepper (sweet and hot) | Apr 3–17 | Jun 26–Jul 10 (transplant) | – |
| Eggplant | Apr 3–17 | Jun 26–Jul 10 (transplant) | – |
| Tomatillo | Apr 17–May 1 | Jun 19–Jul 3 (transplant) | – |
| Lettuce | Apr 17–May 1 | May 22–Jun 12 (transplant) May 15–Jun 26 (sow outdoors) | Jul 16–Aug 6 (transplant) Jul 2–30 (sowing) |
| Spinach | – | May 1–22 (sow outdoors) | Jul 16–Aug 6 (sowing) |
| Kale | Apr 17–May 1 | May 15–29 (transplant) May 15–29 (sow outdoors) | Jun 18–Jul 16 (transplant) Jun 4–Jul 2 (sowing) |
| Collards | Apr 17–May 1 | May 15–Jun 12 (transplant) May 15–Jun 12 (sow outdoors) | Jun 18–Jul 16 (transplant) |
| Broccoli | Apr 3–17 | May 15–29 (transplant) | Jun 4–Jul 2 (transplant) |
| Cabbage | Apr 3–17 | May 15–29 (transplant) | Jun 4–Jul 2 (transplant) |
| Cauliflower | Apr 3–17 | May 29–Jun 12 (transplant) | – |
| Brussels sprouts | Mar 20–Apr 3 | May 15–29 (transplant) | – |
| Kohlrabi | Apr 17–May 1 | May 15–29 (transplant) May 15–29 (sow outdoors) | Jul 2–16 (sowing) |
| Bok choy / Asian greens | – | May 15–29 (sow outdoors) | Jul 16–30 (sowing) |
| Arugula | – | May 15–Jun 12 (sow outdoors) | Jul 16–Aug 13 (sowing) |
| Mustard greens | – | May 15–Jun 5 (sow outdoors) | Jul 16–30 (sowing) |
| Swiss chard | May 1–15 | May 29–Jun 19 (transplant) May 29–Jun 26 (sow outdoors) | Jul 2–16 (sowing) |
| Beet | – | May 15–Jun 12 (sow outdoors) | Jul 2–16 (sowing) |
| Carrot | – | May 22–Jun 19 (sow outdoors) | – |
| Radish | – | May 8–Jun 19 (sow outdoors) | Jul 30–Aug 13 (sowing) |
| Turnip | – | May 15–Jun 5 (sow outdoors) | Jul 2–16 (sowing) |
| Parsnip | – | May 22–Jun 12 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Apr 17–May 15 (sow outdoors) | Jun 18–Jul 2 (sowing) |
| Onion (bulbing) | Mar 20–Apr 3 | May 1–15 (transplant) | – |
| Green onion / scallion | – | May 1–29 (sow outdoors) | Jul 2–16 (sowing) |
| Leek | Mar 20–Apr 3 | May 15–29 (transplant) | – |
| Garlic | – | – | Jul 30–Aug 27 (sowing) |
| Shallot | – | May 1–15 (transplant) | Jul 30–Aug 27 (sowing) |
| Potato | – | May 15–29 (transplant) | – |
| Sweet potato | – | Jul 3–17 (transplant) | – |
| Sweet corn | – | Jun 19–Jul 3 (sow outdoors) | – |
| Bean, bush (snap) | – | Jun 19–Jul 3 (sow outdoors) | – |
| Bean, pole | – | Jun 19–Jul 3 (sow outdoors) | – |
| Lima bean | – | Jun 26–Jul 10 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jul 3–24 (sow outdoors) | – |
| Cucumber | May 15–22 | Jun 19–Jul 3 (transplant) Jun 19–Jul 3 (sow outdoors) | – |
| Summer squash / zucchini | May 15–22 | Jun 19–Jul 3 (transplant) Jun 19–Jul 3 (sow outdoors) | – |
| Winter squash | May 15–22 | Jun 19–Jul 3 (transplant) Jun 19–Jul 3 (sow outdoors) | – |
| Pumpkin | – | Jun 19–Jul 3 (sow outdoors) | – |
| Watermelon | May 15–22 | Jun 26–Jul 10 (transplant) Jun 26–Jul 10 (sow outdoors) | – |
| Cantaloupe / muskmelon | May 15–22 | Jun 26–Jul 10 (transplant) Jun 26–Jul 10 (sow outdoors) | – |
| Okra | May 1–15 | Jun 26–Jul 10 (transplant) Jun 26–Jul 10 (sow outdoors) | – |
| Celery | Mar 20–Apr 3 | Jun 19–26 (transplant) | – |
| Basil | May 1–15 | Jun 19–Jul 3 (transplant) Jun 19–Jul 3 (sow outdoors) | – |
| Cilantro | – | May 29–Jun 26 (sow outdoors) | Jul 16–30 (sowing) |
| Parsley | Apr 3–17 | May 29–Jun 12 (transplant) May 22–Jun 12 (sow outdoors) | – |
| Dill | – | Jun 12–26 (sow outdoors) | Jul 16–30 (sowing) |
| Sunflower | – | Jun 12–26 (sow outdoors) | – |
| Asparagus (crowns) | – | May 15–29 (transplant) | – |
| Rhubarb (crowns) | – | May 15–29 (transplant) | – |
| Strawberry (plants) | – | May 15–29 (transplant) | Jul 2–30 (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 12 here (the average last frost). Not affiliated with the program.
Where these numbers come from
Station: Williams Fork Dam, CO (NOAA GHCN-Daily ID USC00059096), elevation 7,618 ft, 8.5 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Grand Lake 6 SSW, CO | 14 mi | Jun 13 | Sep 7 |
| Kremmling, CO | 17 mi | Jun 14 | Sep 5 |
| Green Mt Dam, CO | 19 mi | Jun 6 | Sep 14 |
The average last-frost dates of these stations span 8 days, a rough guide to local variation. See data sources & methods.
Frost questions for 80451
When is the last frost in 80451?
The average (50% chance) last spring freeze of 32°F for ZIP 80451 is June 12. For a more cautious planting date, use June 25, when only 1 year in 10 still sees a later freeze.
When is the first frost in 80451?
The average first fall freeze is September 10. In 1 year in 10 it comes by August 31.
What hardiness zone is 80451?
ZIP 80451 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 80451 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
80468 Parshall 80478 Tabernash 80446 Granby 80442 Fraser 80482 Winter Park 80459 Kremmling 80447 Grand Lake 80498 Silverthorne
Other ZIP codes in Grand County
80442 80446 80447 80459 80468 80478 80482 All Grand 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.