A Labor Day weekend cold front dropped snow levels in some parts of the Rockies to below 10,000, which is a pretty good indicator that fall is not far off. And so, with that warning, it's only natural to wonder how the fall color displays will be in the national parks.

The general rule of thumb is that aspens and maples in the Rocky Mountain parks (Yellowstone, Grand Teton, Glacier and Rocky Mountain) typically approach their peak vibrance in mid-to-late September.

That said, there already are a few daubs of yellow in the aspen glades in Grand Teton, and in Yellowstone they say some of the ground vegetation is starting to turn red. A good hard frost could hasten things along, but as of now the extended forecast seems to be pointing to a slow turn to fall temperatures.

Looking east, the experts are telling us that the relatively dry summer in the Mid-Atlantic and Southeast states should produce some spectacular fall foliage.

"This should be a pretty good year for leaf color change," says Katherine Mathews, who forecasts fall colors from her office at Western Carolina University. "Although there was enough rainfall this spring to keep the trees healthy, we are still in drought conditions in the western part of the state (North Carolina), which, surprisingly, is good for fall color. Fortunately, the summer temperatures have not been as consistently hot as we had last year, so we should not experience the early leaf drop we had last fall. It all adds up to a nice, long progression of color."

With that in mind, if you're hoping to go in search of fall color, Great Smoky Mountains and Shenandoah national parks would be two pretty good bets for an October getaway. Of course, you're not the only one thinking that way, and so if you don't already have lodging, that could be a problem this late in the game.

Farther north in Maine, the folks at Acadia National Park know exhibit their Yankee upbringing when they say it's foolish to try to predict the peak of fall foliage. However, they note that some trees already are beginning to turn, which is quite a bit ahead of schedule. Plus, heavy rainfall in August has produced some leaf mold that could cause trees to drop their leaves before they reach their peak fall colors.

Typically, coastal Maine is the last part of that state to see fall foliage reach its most vibrant stage, which typically arrives around the middle of October.

To track fall color trends and fine-tune your travel plans, check out the Foliage Network for the latest updates. For Maine-specific reports, check out this site, although it might not yet be operating for this fall.