Climbing the Longs Peak Keyhole Route US National Park Weather on Longs Peak can be volatile. The at the summit of Longs Mountain may vary significantly. It is crucial to keep an eye on the forecast and be ready for any climate conditions hiking on Longs Mountain. The mountain is recognized for its unexpected climate variations and dangerous storms. Choosing the suitable attire in layers and bringing additional gear like precipitation coats, caps, and mittens is crucial to stay protected from the elements.