Fall in zone 5bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 80425 (Jefferson 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, Strontia Springs Dam, CO (7 miles away).
- Average last spring frostMay 1650% chance of a 32°F freeze after this date
- Average first fall frostSep 2950% chance of a 32°F freeze by this date
- Growing season (frost-free)132 daysmedian, 32°F threshold
- USDA hardiness zone5b-15 to -10°F avg. coldest night
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Frost and freeze alerts from the NWS forecast for 80425, 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 (51 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 (51 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 80425 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 3 |
| 50% (the "average" last frost) | May 16 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 6 |
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 16 |
| 50% (the "average" first frost) | Sep 29 |
| 90% (late: most years have frozen by now) | Oct 11 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Jun 1 | Sep 21 |
| 32°F (freeze) | May 16 | Sep 29 |
| 28°F (hard freeze) | May 3 | Oct 8 |
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 80425
Dates count from your average last spring frost (May 16) and first fall frost (Sep 29). 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 | Mar 21–Apr 4 | May 23–Jun 6 (transplant) | – |
| Pepper (sweet and hot) | Mar 7–21 | May 30–Jun 13 (transplant) | – |
| Eggplant | Mar 7–21 | May 30–Jun 13 (transplant) | – |
| Tomatillo | Mar 21–Apr 4 | May 23–Jun 6 (transplant) | – |
| Lettuce | Mar 21–Apr 4 | Apr 25–May 16 (transplant) Apr 18–May 30 (sow outdoors) | Aug 4–25 (transplant) Jul 21–Aug 18 (sowing) |
| Spinach | – | Apr 4–25 (sow outdoors) | Aug 4–25 (sowing) |
| Kale | Mar 21–Apr 4 | Apr 18–May 2 (transplant) Apr 18–May 2 (sow outdoors) | Jul 7–Aug 4 (transplant) Jun 23–Jul 21 (sowing) |
| Collards | Mar 21–Apr 4 | Apr 18–May 16 (transplant) Apr 18–May 16 (sow outdoors) | Jul 7–Aug 4 (transplant) Jun 23–Jul 21 (sowing) |
| Broccoli | Mar 7–21 | Apr 18–May 2 (transplant) | Jun 23–Jul 21 (transplant) |
| Cabbage | Mar 7–21 | Apr 18–May 2 (transplant) | Jun 23–Jul 21 (transplant) |
| Cauliflower | Mar 7–21 | May 2–16 (transplant) | Jun 23–Jul 21 (transplant) |
| Brussels sprouts | Feb 21–Mar 7 | Apr 18–May 2 (transplant) | Jun 9–30 (transplant) |
| Kohlrabi | Mar 21–Apr 4 | Apr 18–May 2 (transplant) Apr 18–May 2 (sow outdoors) | Jul 21–Aug 4 (sowing) |
| Bok choy / Asian greens | – | Apr 18–May 2 (sow outdoors) | Aug 4–18 (sowing) |
| Arugula | – | Apr 18–May 16 (sow outdoors) | Aug 4–Sep 1 (sowing) |
| Mustard greens | – | Apr 18–May 9 (sow outdoors) | Aug 4–18 (sowing) |
| Swiss chard | Apr 4–18 | May 2–23 (transplant) May 2–30 (sow outdoors) | Jul 21–Aug 4 (sowing) |
| Beet | – | Apr 18–May 16 (sow outdoors) | Jul 21–Aug 4 (sowing) |
| Carrot | – | Apr 25–May 23 (sow outdoors) | Jul 7–21 (sowing) |
| Radish | – | Apr 11–May 23 (sow outdoors) | Aug 18–Sep 1 (sowing) |
| Turnip | – | Apr 18–May 9 (sow outdoors) | Jul 21–Aug 4 (sowing) |
| Parsnip | – | Apr 25–May 16 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 21–Apr 18 (sow outdoors) | Jul 7–21 (sowing) |
| Onion (bulbing) | Feb 21–Mar 7 | Apr 4–18 (transplant) | – |
| Green onion / scallion | – | Apr 4–May 2 (sow outdoors) | Jul 21–Aug 4 (sowing) |
| Leek | Feb 21–Mar 7 | Apr 18–May 2 (transplant) | – |
| Garlic | – | – | Aug 18–Sep 15 (sowing) |
| Shallot | – | Apr 4–18 (transplant) | Aug 18–Sep 15 (sowing) |
| Potato | – | Apr 18–May 2 (transplant) | Jun 9–23 (transplant) |
| Sweet potato | – | Jun 6–20 (transplant) | – |
| Sweet corn | – | May 23–Jun 6 (sow outdoors) | – |
| Bean, bush (snap) | – | May 23–Jun 6 (sow outdoors) | – |
| Bean, pole | – | May 23–Jun 6 (sow outdoors) | – |
| Lima bean | – | May 30–Jun 13 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 6–27 (sow outdoors) | – |
| Cucumber | Apr 18–25 | May 23–Jun 6 (transplant) May 23–Jun 6 (sow outdoors) | – |
| Summer squash / zucchini | Apr 18–25 | May 23–Jun 6 (transplant) May 23–Jun 6 (sow outdoors) | – |
| Winter squash | Apr 18–25 | May 23–Jun 6 (transplant) May 23–Jun 6 (sow outdoors) | – |
| Pumpkin | – | May 23–Jun 6 (sow outdoors) | – |
| Watermelon | Apr 18–25 | May 30–Jun 13 (transplant) May 30–Jun 13 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 18–25 | May 30–Jun 13 (transplant) May 30–Jun 13 (sow outdoors) | – |
| Okra | Apr 4–18 | May 30–Jun 13 (transplant) May 30–Jun 13 (sow outdoors) | – |
| Celery | Feb 21–Mar 7 | May 23–30 (transplant) | – |
| Basil | Apr 4–18 | May 23–Jun 6 (transplant) May 23–Jun 6 (sow outdoors) | – |
| Cilantro | – | May 2–30 (sow outdoors) | Aug 4–18 (sowing) |
| Parsley | Mar 7–21 | May 2–16 (transplant) Apr 25–May 16 (sow outdoors) | – |
| Dill | – | May 16–30 (sow outdoors) | Aug 4–18 (sowing) |
| Sunflower | – | May 16–30 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 18–May 2 (transplant) | – |
| Rhubarb (crowns) | – | Apr 18–May 2 (transplant) | – |
| Strawberry (plants) | – | Apr 18–May 2 (transplant) | Jul 21–Aug 18 (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 May 16 here (the average last frost). Not affiliated with the program.
Where these numbers come from
Station: Strontia Springs Dam, CO (NOAA GHCN-Daily ID USC00058022), elevation 5,840 ft, 7.4 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Roxborough Sp, CO | 9 mi | May 16 | Oct 1 |
| Cheesman, CO | 10 mi | May 17 | Oct 1 |
| Kassler, CO | 11 mi | May 8 | Oct 3 |
The average last-frost dates of these stations span 9 days, a rough guide to local variation. See data sources & methods.
Frost questions for 80425
When is the last frost in 80425?
The average (50% chance) last spring freeze of 32°F for ZIP 80425 is May 16. For a more cautious planting date, use June 6, when only 1 year in 10 still sees a later freeze.
When is the first frost in 80425?
The average first fall freeze is September 29. In 1 year in 10 it comes by September 16.
What hardiness zone is 80425?
ZIP 80425 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 80425 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
80470 80135 Sedalia 80433 Aspen Park 80125 Roxborough Park 80127 Dakota Ridge 80131 Louviers 80109 Castle Rock 80128 Columbine
Other ZIP codes in Jefferson County
80002 80003 80004 80005 80007 80021 80033 80123 80127 80128 80214 80215 80226 80227 80228 80232 80235 80401 80403 80419 80433 80453 80454 80457 All Jefferson County frost dates · Colorado frost dates
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- 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.