Yosemite, in February when the fire waterfall appears. The spectacular view of the waterfall is created by the reflection of sunlight hitting the falling water at a specific angle. This rare sight can only be seen at a period towards the end of Feburary.
Be sure to visit, or better yet STAY, at the Ahwahnee Hotel set in the heart of the Valley. it's breathtaking views and amazing architecture will amaze you. One of the best vacations spots I have ever visited!