Once you learn to recognize avalanche terrain, the next step is to recognize whether it will stay put while you're there. Any significant changes in the local weather should be noted and evaluated, as these can have a dramatic impact on the stability of a slope. Events of special concern include rain or warm winds, as well as dramatic increases in temperature or precipitation intensity. Temperatures well above or below freezing can also lead to decreased stability of the snowpack, as can any sudden change in temperature, as these factors affect the relative density of surface layers, as well as the bonding of the crystals within a given layer of the snowpack. It's important to note that weather events are key to developing avalanche hazard.
Most slides occur either during or immediately after a storm or wind-loading event.
Note that even moderate winds can increase the hazard by transporting snow from one area to another, often depositing dangerous slabs on lee slopes in a short period of time. Even at wind speeds of ten miles per hour, snow crystals can be redistributed. Higher wind speeds can cause dramatic erosion of snow on windward slopes and deposition on leeward slopes. Winds with high relative humidity can cause riming of snow crystals, resulting in slick sliding surfaces or deposits of a very cohesive layer of snow. Fresh fractures, blocks of debris and large sunballs are very important clues that snow conditions are unstable and must not be ignored.