Leaf-peeping season has arrived in the Northeast and beyond, but weeks of drought have muted this year’s autumn colors, and sent leaves fluttering to the ground earlier than usual. Soaking in the fall foliage is an annual tradition in the New England states as well as areas such as the Rocky Mountains of Colorado, Great Smoky Mountains of the mid-south and Upper Peninsula of Michigan. As the days shorten and temperatures drop, chlorophyll in leaves breaks down, and they turn to the autumn tones of yellow, orange and red. But dry weather in summer and fall can change all that because it causes leaves to brown and fall more quickly.