East Thermopolis, Wyoming, sits in USDA hardiness zone 5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
The conditions favor cabbage, cranberry, lavender, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Even in East Thermopolis, 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 East Thermopolis 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 East Thermopolis — soil, climate, flood, and parcel records. How we handle your address.
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East Thermopolis — the short answer
East Thermopolis, Wyoming: USDA zone 5a, about 167 days between hard freezes, across 116 acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 26
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 10
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~167
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 116 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 5a is East Thermopolis's average, not your lot's — a low corner or a tree line moves it. Against East Thermopolis's 167-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in East Thermopolis
Each reading below is measured for East Thermopolis itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredEast Thermopolis runs about 167 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredEast Thermopolis sits in USDA hardiness zone 5a.
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 East Thermopolis is in
East Thermopolis sits in the Wyoming Basin — EPA Level III, inside the wider North American Deserts. That is read at East Thermopolis's own centroid rather than borrowed from Hot Springs County.
What Grows in East Thermopolis
Every plant below cleared East Thermopolis's own zone 5a and its 167-day season. Each card opens that plant's Wyoming profile. How we score.
Is it too late to plant in East Thermopolis?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 29; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 26 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 10 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What's on the federal record near East Thermopolis
Closest first, within ~10 miles of East Thermopolis. Listing isn't leaking, and distance isn't exposure.
- ROCKY MOUNTAIN PIPELINE SYSTEMBrownfields · 1000 ft
- HOTSPRINGS CO MEMORIAL HOSPITALBrownfields · 1300 ft
- KTHE Radio StationUnderground Storage Tanks · 1700 ft
- Wyoming Pioneer HomeUnderground Storage Tanks · 2000 ft
- Organizational Maintenance Shop #1CUnderground Storage Tanks · 2200 ft
- 43-095-36cdd01Nitrate · 2200 ft
- UPS - THERMOPOLISBrownfields · 2300 ft
- Hot Springs REA, Inc.Underground Storage Tanks · 2600 ft
- Thermopolis Main 753511Underground Storage Tanks · 0.5 mi
- Hot Springs State ParkUnderground Storage Tanks · 0.5 mi
- Don ChristoffersonUnderground Storage Tanks · 0.5 mi
- 43-095-36acd01Nitrate · 0.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from East Thermopolis'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 East Thermopolis.
Total Sites
83
within ~10 miles of East Thermopolis
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
within ~10 miles of East Thermopolis
Severity Distribution
within ~10 miles of East Thermopolis
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around East Thermopolis, Nitrate runs higher than the national average — 26 sites within ~10 miles of East Thermopolis. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in East Thermopolis
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 East Thermopolis average
Your land is one point inside East Thermopolis
Everything above resolves to East Thermopolis as a whole — one PHZM band and one 28°F frost record, read across 116 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 East Thermopolis Average
East Thermopolis Average
- ●USDA Zones 5a, averaged across East Thermopolis
- ●One soil character for all of East Thermopolis
- ●Frost dates read at East Thermopolis's scale: Apr 26 to Oct 10
YOUR Parcel
- ✓Your exact zone, not East Thermopolis's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in East Thermopolis
Pull a site-specific report for your exact address in East Thermopolis, Wyoming — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that East Thermopolis averages can't show:
We read public map data around East Thermopolis — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the East Thermopolis average
How we know this about East Thermopolis
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 East Thermopolis’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 East Thermopolis
When does frost risk typically end in East Thermopolis?
The last hard freeze (28°F) in East Thermopolis typically lands around Apr 26, 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 May 17.
When is the first frost in East Thermopolis?
The first hard freeze (28°F) in East Thermopolis typically arrives around Oct 10, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 26, so the watching starts about Sep 10 — about 167 days after the spring freeze cleared.
How long is the growing season in East Thermopolis?
Measured between 28°F hard freezes, East Thermopolis sees about 167 frost-free days — roughly Apr 26 through Oct 10, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 17 to Sep 26, about 132 days.
Is the soil safe to grow vegetables in East Thermopolis?
The federal record around East Thermopolis shows 83 documented sites, mostly Underground Storage Tanks entries (42), the nearest Brownfields record about 0.2 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in East Thermopolis?
From about Sep 10 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Oct 10 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Oct 10. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at East Thermopolis's scale — its 5a band and its 167-day season. Your yard writes its own version of East Thermopolis'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 East Thermopolis’s own scale
6 of the readings below were taken at East Thermopolis's own scale — its own ~167-day season between 28°F freezes, the 116 acres it covers and 83 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- East Thermopolis's own USDA hardiness band, zones 5aUSDA PHZM 2023
- East Thermopolis's own 28°F hard-freeze dates, about Apr 26 and Oct 10 and the ~167-day span between themNOAA 1991–2020 Climate Normals
- 83 documented contamination sites on the federal record near East Thermopolis, the closest Brownfields record about 0.2 miles out from the town centreFederal environmental registers
- East Thermopolis's boundary and the 116 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~167-day seasonGrowable Ground crop-matching engine
- The ecoregion at East Thermopolis's own centroid, the Wyoming BasinUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so East Thermopolis's 116 acres read through its county's SSURGO summaryfrom Hot Springs County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Hot Springs 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 Hot Springs County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among East Thermopolis's 116 acreswhy one lot differs from the next →
- Which side of East Thermopolis you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 116 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.2 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 East Thermopolis-wide figureread your own land →
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