Natural hazards are divided into six main groups: Biological, Climatological, Extra-Terrestrial, Geophysical, Hydrological, and Meteorological. Each category can have multiple hazard categories, types and sub-types.
Avalanche centers across Canada and the United States started using a new avalanche danger scale beginning the 2010/11 season. The following are North American Avalanche Danger Level notifications issued: Extreme, High, Considerable, Moderate, and Low.
There is no universally accepted classification of avalanches—different classifications are useful for different purposes. Avalanches can be described by their size, their destructive potential, their initiation mechanism, their composition and their dynamics.
Remember that the avalanche danger rating levels issued by regional avalanche centers are only general guidelines. Distinctions between geographic areas, elevations, slope aspect and slope angle are approximate and transition zones between dangers exist.