Frost dates for ZIP 80310 (Boulder, 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, Boulder, CO (1 miles away).
- Average last spring frostMay 650% chance of a 32°F freeze after this date
- Average first fall frostOct 550% chance of a 32°F freeze by this date
- Growing season (frost-free)151 daysmedian, 32°F threshold
- USDA hardiness zone6a-10 to -5°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
Measured at NOAA USCRN station Boulder 14 W, 15 mi away. Daily averages: Wed 43°, Thu 42°, Fri 40°.
4-inch depth
42°F Below 50°F
24-hour average · latest 45°F, as of Oct 17, 9:00 PM CDT
Measured at NOAA USCRN station Boulder 14 W, 15 mi away. Daily averages: Wed 45°, Thu 44°, Fri 42°.
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 80310 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 42°F at 4 inches. 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) | Apr 24 |
| 50% (the "average" last frost) | May 6 |
| 10% (cautious: only 1 year in 10 freezes later) | May 18 |
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 21 |
| 50% (the "average" first frost) | Oct 5 |
| 90% (late: most years have frozen by now) | Oct 18 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 17 | Sep 28 |
| 32°F (freeze) | May 6 | Oct 5 |
| 28°F (hard freeze) | Apr 27 | Oct 15 |
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 80310
Dates count from your average last spring frost (May 6) and first fall frost (Oct 5). 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 11–25 | May 13–27 (transplant) | – |
| Pepper (sweet and hot) | Feb 25–Mar 11 | May 20–Jun 3 (transplant) | – |
| Eggplant | Feb 25–Mar 11 | May 20–Jun 3 (transplant) | – |
| Tomatillo | Mar 11–25 | May 13–27 (transplant) | – |
| Lettuce | Mar 11–25 | Apr 15–May 6 (transplant) Apr 8–May 20 (sow outdoors) | Aug 10–31 (transplant) Jul 27–Aug 24 (sowing) |
| Spinach | – | Mar 25–Apr 15 (sow outdoors) | Aug 10–31 (sowing) |
| Kale | Mar 11–25 | Apr 8–22 (transplant) Apr 8–22 (sow outdoors) | Jul 13–Aug 10 (transplant) Jun 29–Jul 27 (sowing) |
| Collards | Mar 11–25 | Apr 8–May 6 (transplant) Apr 8–May 6 (sow outdoors) | Jul 13–Aug 10 (transplant) Jun 29–Jul 27 (sowing) |
| Broccoli | Feb 25–Mar 11 | Apr 8–22 (transplant) | Jun 29–Jul 27 (transplant) |
| Cabbage | Feb 25–Mar 11 | Apr 8–22 (transplant) | Jun 29–Jul 27 (transplant) |
| Cauliflower | Feb 25–Mar 11 | Apr 22–May 6 (transplant) | Jun 29–Jul 27 (transplant) |
| Brussels sprouts | Feb 11–25 | Apr 8–22 (transplant) | Jun 15–Jul 6 (transplant) |
| Kohlrabi | Mar 11–25 | Apr 8–22 (transplant) Apr 8–22 (sow outdoors) | Jul 27–Aug 10 (sowing) |
| Bok choy / Asian greens | – | Apr 8–22 (sow outdoors) | Aug 10–24 (sowing) |
| Arugula | – | Apr 8–May 6 (sow outdoors) | Aug 10–Sep 7 (sowing) |
| Mustard greens | – | Apr 8–29 (sow outdoors) | Aug 10–24 (sowing) |
| Swiss chard | Mar 25–Apr 8 | Apr 22–May 13 (transplant) Apr 22–May 20 (sow outdoors) | Jul 27–Aug 10 (sowing) |
| Beet | – | Apr 8–May 6 (sow outdoors) | Jul 27–Aug 10 (sowing) |
| Carrot | – | Apr 15–May 13 (sow outdoors) | Jul 13–27 (sowing) |
| Radish | – | Apr 1–May 13 (sow outdoors) | Aug 24–Sep 7 (sowing) |
| Turnip | – | Apr 8–29 (sow outdoors) | Jul 27–Aug 10 (sowing) |
| Parsnip | – | Apr 15–May 6 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 11–Apr 8 (sow outdoors) | Jul 13–27 (sowing) |
| Onion (bulbing) | Feb 11–25 | Mar 25–Apr 8 (transplant) | – |
| Green onion / scallion | – | Mar 25–Apr 22 (sow outdoors) | Jul 27–Aug 10 (sowing) |
| Leek | Feb 11–25 | Apr 8–22 (transplant) | – |
| Garlic | – | – | Aug 24–Sep 21 (sowing) |
| Shallot | – | Mar 25–Apr 8 (transplant) | Aug 24–Sep 21 (sowing) |
| Potato | – | Apr 8–22 (transplant) | Jun 15–29 (transplant) |
| Sweet potato | – | May 27–Jun 10 (transplant) | – |
| Sweet corn | – | May 13–27 (sow outdoors) | – |
| Bean, bush (snap) | – | May 13–27 (sow outdoors) | – |
| Bean, pole | – | May 13–27 (sow outdoors) | – |
| Lima bean | – | May 20–Jun 3 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 27–Jun 17 (sow outdoors) | – |
| Cucumber | Apr 8–15 | May 13–27 (transplant) May 13–27 (sow outdoors) | – |
| Summer squash / zucchini | Apr 8–15 | May 13–27 (transplant) May 13–27 (sow outdoors) | – |
| Winter squash | Apr 8–15 | May 13–27 (transplant) May 13–27 (sow outdoors) | – |
| Pumpkin | – | May 13–27 (sow outdoors) | – |
| Watermelon | Apr 8–15 | May 20–Jun 3 (transplant) May 20–Jun 3 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 8–15 | May 20–Jun 3 (transplant) May 20–Jun 3 (sow outdoors) | – |
| Okra | Mar 25–Apr 8 | May 20–Jun 3 (transplant) May 20–Jun 3 (sow outdoors) | – |
| Celery | Feb 11–25 | May 13–20 (transplant) | – |
| Basil | Mar 25–Apr 8 | May 13–27 (transplant) May 13–27 (sow outdoors) | – |
| Cilantro | – | Apr 22–May 20 (sow outdoors) | Aug 10–24 (sowing) |
| Parsley | Feb 25–Mar 11 | Apr 22–May 6 (transplant) Apr 15–May 6 (sow outdoors) | – |
| Dill | – | May 6–20 (sow outdoors) | Aug 10–24 (sowing) |
| Sunflower | – | May 6–20 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 8–22 (transplant) | – |
| Rhubarb (crowns) | – | Apr 8–22 (transplant) | – |
| Strawberry (plants) | – | Apr 8–22 (transplant) | Jul 27–Aug 24 (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 6 here (the average last frost). Not affiliated with the program.
Where these numbers come from
Station: Boulder, CO (NOAA GHCN-Daily ID USC00050848), elevation 5,484 ft, 0.9 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Gross Rsvr, CO | 7 mi | May 24 | Sep 23 |
| Coal Creek Canyon, CO | 10 mi | Jun 5 | Sep 16 |
| Ralston Rsvr, CO | 12 mi | May 3 | Oct 14 |
The average last-frost dates of these stations span 33 days, a rough guide to local variation. See data sources & methods.
Frost questions for 80310
When is the last frost in 80310?
The average (50% chance) last spring freeze of 32°F for ZIP 80310 is May 6. For a more cautious planting date, use May 18, when only 1 year in 10 still sees a later freeze.
When is the first frost in 80310?
The average first fall freeze is October 5. In 1 year in 10 it comes by September 21.
What hardiness zone is 80310?
ZIP 80310 is in USDA zone 6a (-10 to -5°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 80310 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
80305 Boulder 80304 Boulder 80303 Boulder 80301 Boulder 80302 Lazy Acres 80025 Eldorado Springs 80027 Louisville 80544 Niwot
Other ZIP codes in Boulder County
80025 80026 80027 80301 80302 80303 80304 80305 80455 80466 80471 80481 80501 80503 80510 80540 80544 All Boulder County frost dates · Colorado frost dates
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