When gaining altitude, be prepared for lower temperatures. The temperature at the peak of a mountain may differ as much as 40 degrees from the temperature at the base of a mountain, even in summer. Evening frosts are known in summer, and snow or sub-freezing temperatures should be expected in spring and fall. Winter temperatures may drop to less than -40 Farenheit, particularly in higher elevations. Rain or snow storms appear quickly wherever you may be in the Park.
Thunder storms rise quickly.
If you are on the water or a mountain summit, get off at the first rumble of thunder. Individual discretion is advised. Some trails are specifically designated as ski trails. Always ski with extra ski-tips. Winter climbing and hiking gear must include crampons, snowshoes, and on some well-used trails, backcountry skis.