Opal, Wyoming, sits in USDA hardiness zone 4b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Crops well matched to these conditions include okra, cranberry, cilantro, and zucchini — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Opal, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Opal lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Opal — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Opal — the short answer
Opal, Wyoming: USDA zone 4b, about 115 days between hard freezes, across 292 acres of town.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 25
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 17
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~115
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 292 acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 4b is Opal's average, not your lot's — a low corner or a tree line moves it. Against Opal's 115-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Opal
Each reading below is measured for Opal itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredOpal runs about 115 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredOpal sits in USDA hardiness zone 4b.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Opal is in
Opal sits in the Wyoming Basin — EPA Level III, inside the wider North American Deserts. That is read at Opal's own centroid rather than borrowed from Lincoln County.
What Grows in Opal
Every plant below cleared Opal's own zone 4b and its 115-day season. Each card opens that plant's Wyoming profile. How we score.
Is it too late to plant in Opal?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 27; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 25 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 17 — long-season crops need about 90 days of runway, quick greens only 30. Even here the calendar’s edges hold value: thirty-day greens late in the window, then garlic and a rested bed for spring.
What's on the federal record near Opal
Closest first, within ~10 miles of Opal. Listing isn't leaking, and distance isn't exposure.
- Don and Annette Peterson Family TrustUnderground Storage Tanks · 800 ft
- Hams Fork SupplyUnderground Storage Tanks · 800 ft
- 21-114-26cbb01Nitrate · 1200 ft
- OPAL GAS PLANTBrownfields · 1300 ft
- OPAL GAS PLANTToxics Release Inventory · 1300 ft
- Opal Section Tool HouseUnderground Storage Tanks · 1300 ft
- 21-114-27dac01Nitrate · 1600 ft
- Resolution Trust CorporationUnderground Storage Tanks · 1800 ft
- 21-114-34aba01Nitrate · 0.5 mi
- PIONEER SILICA GEL PLANTToxics Release Inventory · 1.7 mi
- PIONEER CRYOGENIC PLANTToxics Release Inventory · 1.7 mi
- 21-114-30dcd01Nitrate · 3.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Opal's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Opal.
Total Sites
41
within ~10 miles of Opal
Risk Level
Low
Highest-severity
3 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Opal
Severity Distribution
within ~10 miles of Opal
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Opal, two things run higher than the national average within ~10 miles of Opal — Nitrate (26 sites) and Toxics Release Inventory (3 sites). That's not a problem with your land — it's information about it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Opal
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Opal average
Your land is one point inside Opal
Everything above resolves to Opal as a whole — one PHZM band and one 28°F frost record, read across 292 acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at town scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the Opal Average
Opal Average
- ●USDA Zones 4b, averaged across Opal
- ●One soil character for all of Opal
- ●Frost dates read at Opal's scale: May 25 to Sep 17
YOUR Parcel
- ✓Your exact zone, not Opal's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Opal
Pull a site-specific report for your exact address in Opal, Wyoming — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Opal averages can't show:
We read public map data around Opal — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Opal average
How we know this about Opal
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Opal’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Opal
When does frost risk typically end in Opal?
The last hard freeze (28°F) in Opal typically lands around May 25, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Jun 15.
When is the first frost in Opal?
The first hard freeze (28°F) in Opal typically arrives around Sep 17, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 3, so the watching starts about Aug 18 — about 115 days after the spring freeze cleared.
How long is the growing season in Opal?
Measured between 28°F hard freezes, Opal sees about 115 frost-free days — roughly May 25 through Sep 17, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 15 to Sep 3, about 80 days.
Is the soil safe to grow vegetables in Opal?
The federal record around Opal is light — 41 documented sites across the 9 federal source types we checked, mostly Nitrate entries (26), the nearest Underground Storage Tanks record about 0.1 miles out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do gardeners stretch the season in Opal?
With about 115 frost-free days between hard freezes, Opal rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 143 to 171 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 25 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Opal's scale — its 4b band and its 115-day season. Your yard writes its own version of Opal's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Opal’s own scale
6 of the readings below were taken at Opal's own scale — its own ~115-day season between 28°F freezes, the 292 acres it covers and 41 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Opal's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Opal's own 28°F hard-freeze dates, about May 25 and Sep 17 and the ~115-day span between themNOAA 1991–2020 Climate Normals
- 41 documented contamination sites on the federal record near Opal, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Opal's boundary and the 292 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~115-day seasonGrowable Ground crop-matching engine
- The ecoregion at Opal's own centroid, the Wyoming BasinUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Opal's 292 acres read through its county's SSURGO summaryfrom Lincoln County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Lincoln County
- The growing challenges every Wyoming grower plans around — written at state scale, so they stay on the state guidefrom Wyoming
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Lincoln County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Opal's 292 acreswhy one lot differs from the next →
- Which side of Opal you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 292 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.1 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Opal-wide figureread your own land →
More in Wyoming
Wider growing context
What grows across WyomingOpal sits outside our named growing regions, so Wyoming as a whole is its closest context here.
Nearby growing guides