GMS Difficulty Ratings

Simplified Calendar Difficulty Rating

This is the rating seen as a "D" number under each event on calendar, as well as in the "Difficulty Rating" field in the event description pages.
These numbers match to the overall rating from the GMS Climb Classification (see below).
For a more detailed rating open the event and read the itinerary for the Full GMS Classification.

D1 = Class I
D2 = Class II
D3 = Class III
D4 = Class IV
D5 = Class V
D6 - Class VI

GMS Climb Classification System

For a more detailed rating of the summer climbs you will have to open the event description and read the Itinerary. At the top of that section there should be a rating like "III(4)MM"

Class I (1) Easy
Trail hiking

Class II (2) Moderate
Low angle scrambling.

Class III (3) Difficult
High angle scrambling, moderate cliffs, considerable exertion. Rope might be necessary for beginners.
Class IV (4) Very Difficult
Higher angle cliffs, increased exposure. Belaying rope required.

Class V (5) Severe
High angle cliffs, severe exposure. Protection placed by leader. Technical climbing experience necessary.

Class VI (6) Extremely Severe
Direct aid technical climbing. Overall rating in the classification reserved for only the biggest technical climbs. (example North Face of Mt. Siyeh or East Face of Mt. Gould)
S - 1 to 6 miles
M - 6 to 12 miles
L - 12 to 20 miles
S - Less than 3,000ft.
M - 3,000 to 4,500ft.
L - Over 4,500ft.
Route Symbols
(AL) Alpine
(T) Traverse
(I) Ice or Snow likely
(X) Exploratory

Winter Classification System

We do not use the GMS Classification system for winter events since most winter events are strictly snowshoe or ski and don't involve climbing.
Instead we rate based on avalanche terrain exposure. It is based on the The Parks Canada ATES system.
This rating is intended to supplement pre-trip planning research and is not a substitute for avalanche safety research and education. It is to help participants assess their personal risk level before and during an event.

Class 1 - Simple: Exposure to low angle or primarily forested terrain. Some forest openings may involve the runout zones of infrequent avalanches. Many options to reduce or eliminate exposure.

Class 2 - Challenging: Exposure to well-defined avalanche paths, starting zones or terrain traps; options exist to reduce or eliminate exposure with careful route finding.

Class 3 - Complex: Exposure to multiple overlapping avalanche paths or large expanses of steep, open terrain; multiple avalanche starting zones and terrain traps below; minimal options to reduce exposure.