FrostList

When to Prevent Ice Dams in Cheyenne, WY

ON TRACK96 days until snow season (estimated)Oct 15

Ice dams become a risk in Cheyenne once snow settles on the roof, which typically starts near October 15 (NOAA snowfall normals, about 66" a year), so prep the attic and roof edge before then. The early-to-late range spans roughly 26 days, so treat the median as a midpoint, not a promise.

OUTLOOK

Typical first snow season (estimated) near Oct 15; local deadline about Sep 15. The live 10-day outlook loads here.

Local freeze dates for Cheyenne

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Sep 17Oct 1Oct 14
28°F (hard freeze)Sep 27Oct 10Oct 23
24°F (severe)Oct 4Oct 19Nov 3

NOAA station: Cheyenne WFO · 1.1 mi away · 6,119 ft elevation.

For Cheyenne, the nearest NOAA station with freeze data is Cheyenne WFO, 1.1 miles out at 6,119 feet. Median first-freeze dates there run 32°F by Oct 1, 28°F by Oct 10, 24°F by Oct 19. Year to year the 28°F date has ranged from Sep 27 to Oct 23 — about 26 days apart. Spring's last 32°F freeze clears around May 14. Snowfall averages 66 inches a year, first reaching an inch near October.

Cheyenne usually sees its first 32°F night about Oct 1, with the first 28°F hard freeze close behind near Oct 10. The 32°F date swings from Sep 17 at its earliest to Oct 14 at its latest, near 27 days. The last spring freeze averages May 14 and as late as May 28, which sets the safe window for reopening outdoor water and de-winterizing gear. Roughly 66 inches of snow fall in an average year, so a clear roof edge and a running snow blower matter as much as the freeze itself.

Your ice dams checklist

  1. Before snow flies, seal attic air leaks around lights, the attic hatch, and plumbing stacks so warm air stays out of the attic.
  2. Add insulation to bring the attic floor up to a deep, even blanket; a cold roof deck is what stops dams from forming.
    Helpful gear: Attic vent baffles — Recommended pick
  3. Confirm soffit and ridge vents are open and clear so outside air keeps the underside of the roof cold.
  4. After a storm drops four inches or more, rake the lower three to six feet of roof from the ground.
    Helpful gear: 21-foot roof rake — Recommended pick
  5. Keep a safe distance from the edge while raking and never climb an icy roof; work from the ground.
  6. If a dam forms, lay a calcium-chloride melt sock across it to open a drainage channel — do not chip at the ice.
    Helpful gear: Calcium chloride roof-melt socks — Recommended pick
  7. For a roof that dams every year, have heat cable installed at the eaves before the season starts.
    Helpful gear: Roof de-icing heat cable — Recommended pick
  8. Watch for long icicles and interior ceiling stains; both are early signs water is backing up under the shingles.

What to have on hand

21-foot roof rake
Telescoping rake that clears the lower roof edge from the ground.
Recommended pick
Calcium chloride roof-melt socks
Filled tubes laid across the eave to open a drainage channel.
Recommended pick
Roof de-icing heat cable
Zig-zag cable that keeps a melt path open at the eaves.
Recommended pick
Attic vent baffles
Chutes that keep soffit airflow open so the roof stays cold.
Recommended pick

What this means locally

Cheyenne freezes close to Fort Collins (Oct 15) and close to Greeley (Oct 15) — a reminder that even nearby towns differ by days. Statewide, Wyoming prep dates run Aug 16 through Sep 15, which is why Cheyenne gets its own number rather than a Wyoming-wide average. The same freeze also decides when to guard your pipes and ready your snow blower.

Other winter jobs in Cheyenne

Every task below is dated to Cheyenne's own freeze and snow normals.

Sprinklers → Sep 30Frozen pipes → Sep 17Car battery → Oct 10Snow blower → Sep 24Sump pump → May 14RV → Sep 30Boat → Oct 3Motorcycle → Oct 1

See the full Cheyenne winter checklist, in order →

Frequently asked questions

What causes ice dams?
Heat escaping into the attic warms the roof deck and melts the underside of the snowpack. That meltwater runs down to the cold eave, where it refreezes into a ridge of ice. The dam then traps later melt, which can back up under the shingles. University Extension programs point to attic heat loss as the root cause.
How much snow on a roof causes ice dams?
There is no single number, but several inches of snow that lingers gives dams the material they need, especially when days rise above freezing and nights fall below. A roof that sheds snow quickly or stays uniformly cold rarely dams. Watch for snow that sticks around through a stretch of thaw-freeze weather.
Do heat cables prevent ice dams?
Heat cables do not fix the underlying attic-heat problem, but installed in a zig-zag at the eaves they can keep a melt path open so water drains instead of pooling. They work best as one part of a plan that also includes air sealing, insulation, and ventilation. Run them only when needed to save energy.
Is roof raking worth it?
Removing the lower three to six feet of snow from the ground after a storm takes away the material a dam forms from, and it is one of the safest do-it-yourself steps. Use a roof rake with an extension and keep clear of the edge. Never climb onto an icy roof to rake.
Will my insurance cover ice dam damage?
Many homeowner policies cover sudden interior water damage from an ice dam, but coverage and deductibles vary, and repeated damage may raise questions about maintenance. Document the damage with photos. Preventing dams through attic work is cheaper and less disruptive than filing repeat claims.
How do I know if I have an ice dam forming?
Look for a thick ridge of ice at the eaves, large icicles hanging from the gutters, and water stains on interior ceilings or the tops of exterior walls. Icicles alone are not proof, but combined with a warm attic and lingering roof snow they are a warning worth acting on.

Data: NOAA 1991–2020 normals via Cheyenne WFO, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.