New ice is usually stronger than old ice. As ice ages, the bond between the crystals makes it more dangerous and weaker even if melting has not occurred. Wind speeds influence ice formation. Light winds speed up the formation. Strong winds force water from beneath the ice and can decay the edges of the ice.
Snow can insulate ice and keep it strong.
It can also insulate it to keep it from freezing. When ice is covered by snow, great precautions need to be taken to determine ice thickness before starting any activity. Snow can also hide cracked, weak and open water areas. Slush is a danger sign. Slush indicates that ice is no longer freezing from the bottom.