A new crispness in the air. The red, orange and yellow of the leaves changing colors. The crunch of the first few leaves on the ground.

On that inevitable march toward winter, there are still a few weeks for the casual and determined leaf peeper alike to enjoy the leaves changing color before they fall.

Never mind that it happens every year. "It's because it's fleeting is why it's new every year," says Mel Allen, editor of Yankee Magazine. In each of his 33 years at the magazine leaf peeping has been a fall cover story.

"It's fall and the leaves are becoming beautiful; apple orchards; and the hawks are flying overhead. It's a sensual experience," he says.

"If you were to talk to someone in New Orleans who had had 33 Mardi Gras, they'd still be excited about it," says Allen. "This is our party."

Different shades of red, orange and yellow

While evergreen trees such as pines and spruces have foliage that has evolved to survive extreme temperature changes, deciduous (broad-leaved) trees have evolved to drop their leaves and go dormant for the winter, says Ed Sharron, a science communication specialist with the National Park Service's Northeast Temperate Network in Vermont.

"It's such stark contrast," says Sharron, who's based at Marsh Billings Rockefeller National Historical Park in Woodstock, Vermont. "There are different shades of green, of course, when you start to get that variation of oranges and reds and purples and greens all together. It's pretty spectacular."

Trees that "have been stressed throughout the year by extensive drought or many other factors, they may decide to pack it in early and go dormant for the winter sooner than during a typical year," Sharron says. "This could cause their leaves to fall off sooner or be browner than normal. Every year is different and you never can tell how good the foliage season is going to be until it's here."

The Northeast's most popular sites

Who cares if it's cliché to say that first-time leaf peepers should drive New Hampshire's Kancamagus Highway; visit Woodstock or Smuggler's Notch in Vermont, or head north to Acadia National Park in Maine?

"There's a reason why they're so popular, and these are places I try to go to every year," says Jim Salge, a New Hampshire-based trained meteorologist and high school physics teacher who blogs about the fall foliage season for Yankee Magazine.

If Salge has an extra day this year, he'll head to Dixville Notch in far northern New Hampshire, where the leaves are likely to peak by late September. "The mountains are really jagged and have a feel unlike anywhere else in the Northeast."

Between North and South

Northern and Southern trees meet peacefully at the Delaware Water Gap National Recreation Area, a National Park Service area that includes the states of New Jersey and Pennsylvania.

"In the Delaware Gap I think we have some of the best fall foliage," says Kathleen Sandt, a park ranger in the national recreation area. "We are on the border of northern species that usually don't come down south and the border for some of the trees that grow in the southern region."

The gap is also home to trees living at different elevations. There are sycamores, elms, maples, poplars on a fertile flood plain along the river. At higher elevations, there are various types of oaks and maples to see as hikers head up toward the mountains.

Tree spotters may be pleased to spot the American larch, a deciduous conifer that isn't found much farther south. It's a rare combination of a deciduous tree, which means it loses its leaves each fall; and a conifer, which has needles and cones. In the fall the larch's needles turn bright yellow and fall, like leaves.

"It grows in wetter areas in the park, and it's spectacular in the fall," Sandt says.

Head north to Maine country