Fall in zone 6aPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 84121 (Brighton, UT)
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, Alta, UT (3 miles away).
- Average last spring frostJun 1150% chance of a 32°F freeze after this date
- Average first fall frostSep 1850% chance of a 32°F freeze by this date
- Growing season (frost-free)98 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 18, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
50°F 50–55°F
24-hour average · latest 48°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Morgan (26 mi), Grantsville (37 mi), Chicken Ridge (53 mi).
4-inch depth
51°F 50–55°F
24-hour average · latest 51°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Morgan (26 mi), Grantsville (37 mi), Chicken Ridge (53 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 84121 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 51°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 26 |
| 50% (the "average" last frost) | Jun 11 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 27 |
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 3 |
| 50% (the "average" first frost) | Sep 18 |
| 90% (late: most years have frozen by now) | Sep 29 |
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 11 | Sep 18 |
| 28°F (hard freeze) | Jun 1 | Sep 27 |
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 84121
Dates count from your average last spring frost (Jun 11) and first fall frost (Sep 18). 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 16–30 | Jun 18–Jul 2 (transplant) | – |
| Pepper (sweet and hot) | Apr 2–16 | Jun 25–Jul 9 (transplant) | – |
| Eggplant | Apr 2–16 | Jun 25–Jul 9 (transplant) | – |
| Tomatillo | Apr 16–30 | Jun 18–Jul 2 (transplant) | – |
| Lettuce | Apr 16–30 | May 21–Jun 11 (transplant) May 14–Jun 25 (sow outdoors) | Jul 24–Aug 14 (transplant) Jul 10–Aug 7 (sowing) |
| Spinach | – | Apr 30–May 21 (sow outdoors) | Jul 24–Aug 14 (sowing) |
| Kale | Apr 16–30 | May 14–28 (transplant) May 14–28 (sow outdoors) | Jun 26–Jul 24 (transplant) Jun 12–Jul 10 (sowing) |
| Collards | Apr 16–30 | May 14–Jun 11 (transplant) May 14–Jun 11 (sow outdoors) | Jun 26–Jul 24 (transplant) Jun 12–Jul 10 (sowing) |
| Broccoli | Apr 2–16 | May 14–28 (transplant) | Jun 12–Jul 10 (transplant) |
| Cabbage | Apr 2–16 | May 14–28 (transplant) | Jun 12–Jul 10 (transplant) |
| Cauliflower | Apr 2–16 | May 28–Jun 11 (transplant) | Jun 12–Jul 10 (transplant) |
| Brussels sprouts | Mar 19–Apr 2 | May 14–28 (transplant) | May 29–Jun 19 (transplant) |
| Kohlrabi | Apr 16–30 | May 14–28 (transplant) May 14–28 (sow outdoors) | Jul 10–24 (sowing) |
| Bok choy / Asian greens | – | May 14–28 (sow outdoors) | Jul 24–Aug 7 (sowing) |
| Arugula | – | May 14–Jun 11 (sow outdoors) | Jul 24–Aug 21 (sowing) |
| Mustard greens | – | May 14–Jun 4 (sow outdoors) | Jul 24–Aug 7 (sowing) |
| Swiss chard | Apr 30–May 14 | May 28–Jun 18 (transplant) May 28–Jun 25 (sow outdoors) | Jul 10–24 (sowing) |
| Beet | – | May 14–Jun 11 (sow outdoors) | Jul 10–24 (sowing) |
| Carrot | – | May 21–Jun 18 (sow outdoors) | Jun 26–Jul 10 (sowing) |
| Radish | – | May 7–Jun 18 (sow outdoors) | Aug 7–21 (sowing) |
| Turnip | – | May 14–Jun 4 (sow outdoors) | Jul 10–24 (sowing) |
| Parsnip | – | May 21–Jun 11 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Apr 16–May 14 (sow outdoors) | Jun 26–Jul 10 (sowing) |
| Onion (bulbing) | Mar 19–Apr 2 | Apr 30–May 14 (transplant) | – |
| Green onion / scallion | – | Apr 30–May 28 (sow outdoors) | Jul 10–24 (sowing) |
| Leek | Mar 19–Apr 2 | May 14–28 (transplant) | – |
| Garlic | – | – | Aug 7–Sep 4 (sowing) |
| Shallot | – | Apr 30–May 14 (transplant) | Aug 7–Sep 4 (sowing) |
| Potato | – | May 14–28 (transplant) | May 29–Jun 12 (transplant) |
| Sweet potato | – | Jul 2–16 (transplant) | – |
| Sweet corn | – | Jun 18–Jul 2 (sow outdoors) | – |
| Bean, bush (snap) | – | Jun 18–Jul 2 (sow outdoors) | – |
| Bean, pole | – | Jun 18–Jul 2 (sow outdoors) | – |
| Lima bean | – | Jun 25–Jul 9 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jul 2–23 (sow outdoors) | – |
| Cucumber | May 14–21 | Jun 18–Jul 2 (transplant) Jun 18–Jul 2 (sow outdoors) | – |
| Summer squash / zucchini | May 14–21 | Jun 18–Jul 2 (transplant) Jun 18–Jul 2 (sow outdoors) | – |
| Winter squash | May 14–21 | Jun 18–Jul 2 (transplant) Jun 18–Jul 2 (sow outdoors) | – |
| Pumpkin | – | Jun 18–Jul 2 (sow outdoors) | – |
| Watermelon | May 14–21 | Jun 25–Jul 9 (transplant) Jun 25–Jul 9 (sow outdoors) | – |
| Cantaloupe / muskmelon | May 14–21 | Jun 25–Jul 9 (transplant) Jun 25–Jul 9 (sow outdoors) | – |
| Okra | Apr 30–May 14 | Jun 25–Jul 9 (transplant) Jun 25–Jul 9 (sow outdoors) | – |
| Celery | Mar 19–Apr 2 | Jun 18–25 (transplant) | – |
| Basil | Apr 30–May 14 | Jun 18–Jul 2 (transplant) Jun 18–Jul 2 (sow outdoors) | – |
| Cilantro | – | May 28–Jun 25 (sow outdoors) | Jul 24–Aug 7 (sowing) |
| Parsley | Apr 2–16 | May 28–Jun 11 (transplant) May 21–Jun 11 (sow outdoors) | – |
| Dill | – | Jun 11–25 (sow outdoors) | Jul 24–Aug 7 (sowing) |
| Sunflower | – | Jun 11–25 (sow outdoors) | – |
| Asparagus (crowns) | – | May 14–28 (transplant) | – |
| Rhubarb (crowns) | – | May 14–28 (transplant) | – |
| Strawberry (plants) | – | May 14–28 (transplant) | Jul 10–Aug 7 (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.
Where these numbers come from
Station: Alta, UT (NOAA GHCN-Daily ID USC00420072), elevation 8,710 ft, 3.2 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Cottonwood Weir, UT | 5 mi | Apr 29 | Oct 22 |
| Mtn Dell Dam, UT | 9 mi | May 7 | Oct 14 |
| Park City, UT | 10 mi | May 29 | Sep 25 |
The average last-frost dates of these stations span 44 days, a rough guide to local variation. See data sources & methods.
Frost questions for 84121
When is the last frost in 84121?
The average (50% chance) last spring freeze of 32°F for ZIP 84121 is June 11. For a more cautious planting date, use June 27, when only 1 year in 10 still sees a later freeze.
When is the first frost in 84121?
The average first fall freeze is September 18. In 1 year in 10 it comes by September 3.
What hardiness zone is 84121?
ZIP 84121 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 84121 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
84092 Sandy 84109 Millcreek 84124 Millcreek 84093 Sandy 84117 Holladay 84004 Alpine 84060 Park City 84094 Sandy
Other ZIP codes in Salt Lake County
84006 84009 84020 84044 84047 84065 84070 84081 84084 84088 84092 84093 84094 84095 84096 84101 84102 84103 84104 84105 84106 84107 84108 84109 All Salt Lake County frost dates · Utah 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.