Longs Peak Rocky Mountain National Park US National Park Weather on Longs Mountain may be fickle. The weather atop Longs Summit could vary greatly. It is vital to keep an eye on the weather forecast and be ready for any weather conditions before Longs Summit. The is renowned for its abrupt weather shifts as well as hazardous storms. Choosing the suitable attire in layers and carrying additional gear like rain coats, hats, and gloves is crucial to stay sheltered against the elements.