Fall in zone 4bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 82190 (Mammoth, WY)
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, Yellowstone Park Mammoth, WY (32 miles away).
Station is a bit far
The nearest station with freeze normals is over 40 km away, so dates here may be off by a week or more.
- Average last spring frostJun 350% chance of a 32°F freeze after this date
- Average first fall frostSep 1450% chance of a 32°F freeze by this date
- Growing season (frost-free)102 daysmedian, 32°F threshold
- USDA hardiness zone4b-25 to -20°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
45°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 Moose 1 NNE (59 mi).
4-inch depth
46°F Below 50°F
24-hour average · latest 46°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Moose 1 NNE (59 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 82190 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 46°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 18 |
| 50% (the "average" last frost) | Jun 3 |
| 10% (cautious: only 1 year in 10 freezes later) | Jun 19 |
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 14 |
| 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) | n/a | n/a |
| 32°F (freeze) | Jun 3 | Sep 14 |
| 28°F (hard freeze) | May 16 | Sep 29 |
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 82190
Dates count from your average last spring frost (Jun 3) and first fall frost (Sep 14). 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 8–22 | Jun 10–24 (transplant) | – |
| Pepper (sweet and hot) | Mar 25–Apr 8 | Jun 17–Jul 1 (transplant) | – |
| Eggplant | Mar 25–Apr 8 | Jun 17–Jul 1 (transplant) | – |
| Tomatillo | Apr 8–22 | Jun 10–24 (transplant) | – |
| Lettuce | Apr 8–22 | May 13–Jun 3 (transplant) May 6–Jun 17 (sow outdoors) | Jul 20–Aug 10 (transplant) Jul 6–Aug 3 (sowing) |
| Spinach | – | Apr 22–May 13 (sow outdoors) | Jul 20–Aug 10 (sowing) |
| Kale | Apr 8–22 | May 6–20 (transplant) May 6–20 (sow outdoors) | Jun 22–Jul 20 (transplant) Jun 8–Jul 6 (sowing) |
| Collards | Apr 8–22 | May 6–Jun 3 (transplant) May 6–Jun 3 (sow outdoors) | Jun 22–Jul 20 (transplant) Jun 8–Jul 6 (sowing) |
| Broccoli | Mar 25–Apr 8 | May 6–20 (transplant) | Jun 8–Jul 6 (transplant) |
| Cabbage | Mar 25–Apr 8 | May 6–20 (transplant) | Jun 8–Jul 6 (transplant) |
| Cauliflower | Mar 25–Apr 8 | May 20–Jun 3 (transplant) | Jun 8–Jul 6 (transplant) |
| Brussels sprouts | Mar 11–25 | May 6–20 (transplant) | May 25–Jun 15 (transplant) |
| Kohlrabi | Apr 8–22 | May 6–20 (transplant) May 6–20 (sow outdoors) | Jul 6–20 (sowing) |
| Bok choy / Asian greens | – | May 6–20 (sow outdoors) | Jul 20–Aug 3 (sowing) |
| Arugula | – | May 6–Jun 3 (sow outdoors) | Jul 20–Aug 17 (sowing) |
| Mustard greens | – | May 6–27 (sow outdoors) | Jul 20–Aug 3 (sowing) |
| Swiss chard | Apr 22–May 6 | May 20–Jun 10 (transplant) May 20–Jun 17 (sow outdoors) | Jul 6–20 (sowing) |
| Beet | – | May 6–Jun 3 (sow outdoors) | Jul 6–20 (sowing) |
| Carrot | – | May 13–Jun 10 (sow outdoors) | Jun 22–Jul 6 (sowing) |
| Radish | – | Apr 29–Jun 10 (sow outdoors) | Aug 3–17 (sowing) |
| Turnip | – | May 6–27 (sow outdoors) | Jul 6–20 (sowing) |
| Parsnip | – | May 13–Jun 3 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Apr 8–May 6 (sow outdoors) | Jun 22–Jul 6 (sowing) |
| Onion (bulbing) | Mar 11–25 | Apr 22–May 6 (transplant) | – |
| Green onion / scallion | – | Apr 22–May 20 (sow outdoors) | Jul 6–20 (sowing) |
| Leek | Mar 11–25 | May 6–20 (transplant) | – |
| Garlic | – | – | Aug 3–31 (sowing) |
| Shallot | – | Apr 22–May 6 (transplant) | Aug 3–31 (sowing) |
| Potato | – | May 6–20 (transplant) | May 25–Jun 8 (transplant) |
| Sweet potato | – | Jun 24–Jul 8 (transplant) | – |
| Sweet corn | – | Jun 10–24 (sow outdoors) | – |
| Bean, bush (snap) | – | Jun 10–24 (sow outdoors) | – |
| Bean, pole | – | Jun 10–24 (sow outdoors) | – |
| Lima bean | – | Jun 17–Jul 1 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Jun 24–Jul 15 (sow outdoors) | – |
| Cucumber | May 6–13 | Jun 10–24 (transplant) Jun 10–24 (sow outdoors) | – |
| Summer squash / zucchini | May 6–13 | Jun 10–24 (transplant) Jun 10–24 (sow outdoors) | – |
| Winter squash | May 6–13 | Jun 10–24 (transplant) Jun 10–24 (sow outdoors) | – |
| Pumpkin | – | Jun 10–24 (sow outdoors) | – |
| Watermelon | May 6–13 | Jun 17–Jul 1 (transplant) Jun 17–Jul 1 (sow outdoors) | – |
| Cantaloupe / muskmelon | May 6–13 | Jun 17–Jul 1 (transplant) Jun 17–Jul 1 (sow outdoors) | – |
| Okra | Apr 22–May 6 | Jun 17–Jul 1 (transplant) Jun 17–Jul 1 (sow outdoors) | – |
| Celery | Mar 11–25 | Jun 10–17 (transplant) | – |
| Basil | Apr 22–May 6 | Jun 10–24 (transplant) Jun 10–24 (sow outdoors) | – |
| Cilantro | – | May 20–Jun 17 (sow outdoors) | Jul 20–Aug 3 (sowing) |
| Parsley | Mar 25–Apr 8 | May 20–Jun 3 (transplant) May 13–Jun 3 (sow outdoors) | – |
| Dill | – | Jun 3–17 (sow outdoors) | Jul 20–Aug 3 (sowing) |
| Sunflower | – | Jun 3–17 (sow outdoors) | – |
| Asparagus (crowns) | – | May 6–20 (transplant) | – |
| Rhubarb (crowns) | – | May 6–20 (transplant) | – |
| Strawberry (plants) | – | May 6–20 (transplant) | Jul 6–Aug 3 (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: Yellowstone Park Mammoth, WY (NOAA GHCN-Daily ID USC00489905), elevation 6,195 ft, 31.6 miles from the ZIP's center point. NOAA completeness flag: S (standard, 24+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Gardiner, MT | 35 mi | May 21 | Sep 27 |
| Hebgen Dam, MT | 42 mi | Jun 15 | Sep 10 |
| Ashton 1N, ID | 51 mi | May 21 | Sep 21 |
The average last-frost dates of these stations span 25 days, a rough guide to local variation. See data sources & methods.
Frost questions for 82190
When is the last frost in 82190?
The average (50% chance) last spring freeze of 32°F for ZIP 82190 is June 3. For a more cautious planting date, use June 19, when only 1 year in 10 still sees a later freeze.
When is the first frost in 82190?
The average first fall freeze is September 14. In 1 year in 10 it comes by August 31.
What hardiness zone is 82190?
ZIP 82190 is in USDA zone 4b (-25 to -20°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 82190 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
59758 West Yellowstone 83433 Island Park 83013 83429 Island Park 59030 Jardine 83420 Warm River 59081 Silver Gate 83414 Alta
Other ZIP codes in Park County
82414 82433 82435 82440 82450 All Park County frost dates · Wyoming frost dates
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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.