Hope for an overcast day or clearing storm that leaves mist of plenty of clouds in the sky to obscure the bright sun. Bright sun will make it impossible to capture the vibrant colors in the aspens, especially if you're after grand landscapes. On the other hand, backlit aspens in bright late afternoon or early morning sunshine make a great image.
You want to be here for the peak of the fall colors in the vast aspen forests of western Colorado. This image was taken along Kebler Pass the first week of October 2011.