An avalanche terrain risk reference helps backcountry travelers understand which slopes and terrain features are most dangerous. Slope angle is the single most important predictor of avalanche occurrence — most slides happen on 30°–45° slopes. Always check your regional avalanche center forecast before any winter backcountry travel.
Slope Angle Risk Lookup
Slope Angle Risk Reference
| Angle | Risk Level | Notes |
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Dangerous Terrain Features
How to Use the Avalanche Terrain Risk Reference
Understanding avalanche terrain starts with slope angle but goes far beyond it. This reference covers the key factors that determine whether a slope is dangerous and what to do about it. The slider above gives instant risk context for any slope reading.
Step 1: Read the Avalanche Forecast First
Before going anywhere near avalanche terrain, check the forecast from your regional avalanche center (avalanche.org in the US, avalanche.ca in Canada). The five-level danger scale (Low 1, Moderate 2, Considerable 3, High 4, Extreme 5) tells you how reactive the snowpack is that day. Slope angle is always dangerous — a Considerable or High day means even slopes below 38° may be triggered.
Step 2: Identify 30°+ Slopes and Aspect
Slopes between 30° and 45° are the prime avalanche zone. Use a slope angle meter (inclinometer) or mapping apps like Gaia GPS and Caltopo with slope angle shading enabled. Aspect (which direction a slope faces) determines whether recent wind loading or solar radiation has affected the snowpack stability.
Step 3: Recognize Terrain Traps
Even a small avalanche can be fatal if it carries you into a terrain trap. A gully, cliff band, creek bed, or dense trees can cause fatal burial or trauma from a slide that would otherwise be survivable on open terrain. Avoid terrain traps whenever avalanche danger is Considerable or higher.
Step 4: Carry and Know Your Safety Gear
The standard avalanche safety kit is beacon (transceiver) + probe + shovel. All members of the group must carry all three and know how to use them. Practice beacon searches before the season. The survival rate from burial drops dramatically after 15 minutes — rapid companion rescue is the only effective response in the backcountry where helicopter response times are 30+ minutes.
FAQ
Is this avalanche risk guide free?
Yes, completely free with no signup. This is a general reference guide for educational purposes.
Is my data safe and private?
Yes. This is a reference tool. Everything runs in your browser with no data collection.
What slope angles cause avalanches?
Most avalanches occur on slopes between 30° and 45°. Slopes steeper than 45° tend to sluff (continuously shed) rather than accumulate enough snow to avalanche. Slopes under 30° rarely avalanche but can be caught in runout zones. The most dangerous angles are 35°–40°.
What is a terrain trap in avalanche safety?
A terrain trap is a terrain feature that dramatically increases burial depth or trauma if you are caught in an avalanche. Examples include gullies (avalanche funnels), cliff bands below (you get carried over), trees (trauma), and flat areas where debris accumulates deeply. Even a small avalanche on a terrain trap can be fatal.
What is the AIARE avalanche decision framework?
AIARE (American Institute for Avalanche Research and Education) teaches a structured decision framework: Plan (check forecast, identify hazards), Ride (manage terrain, travel one at a time), Rescue (train to respond). The key tool is the avalanche forecast from your regional avalanche center, updated daily on a 1–5 danger scale.
Should I always carry avalanche safety gear?
Yes, if traveling in avalanche terrain. The standard kit is beacon (transceiver) + probe + shovel. All three are required for organized rescue — a beacon without a probe and shovel is nearly useless for companion rescue. ABS airbag packs can help prevent burial but do not replace the BPS kit. Take an avalanche safety course before venturing into the backcountry.