Foliage forecasts are bullish, despite summer’s heat. Here’s what leaf peepers in Philly and elsewhere can expect.

The romances of the oaks and the vagaries of the atmosphere notwithstanding, the experts believe that the Philly region, the Northeast, and the Mid-Atlantic are in for at least a decent, and possibly brilliant, foliage season.

Despite what was one of the warmest summers on record in the Northeast — it was Philly’s fourth warmest — veteran foliage watchers like what they’re seeing and what the peeping public may see in the weeks to come.

So far, conditions along the major view corridors have been favorable for the leaves of the deciduous trees to turn to gold and red, yellow and cinnamon on cue from Maine to North Carolina.

» READ MORE: The warm summer wasn't exactly new

“New England all the way down to the Blue Ridges, it really does look good this year,” said meteorologist Jim Salge, veteran foliage forecaster for Yankee magazine.

Philadelphia happens to be well situated, in driving distance to spectacular wooded areas, including the Blue Ridges, the Poconos, the Adirondacks, the Berkshires, and the Green and White Mountains.

In the most recent interagency U.S. Drought Monitor report, none of those areas was in anything approaching serious, leaf-killing drought, a mortal enemy of fall color. Saturating, color-diluting, fungi-producing rains have been evident only in far northeastern Vermont, Salge noted.

And September is off to an excellent start, said William G. Cullina, executive director of Philadelphia’s Morris Arboretum.

“This recent stretch of dry, sunny weather should really help the fall colors this season,” he said.

Central Pennsylvania forests “look robust and healthy,” said Marc Abrams, a Pennsylvania State University forestry specialist who has been monitoring foliage conditions for over 30 years. “I think we are in good shape for a nice display.”

Said Ryan Reed, with the Pennsylvania Bureau of Forestry and a keeper of the state’s excellent weekly foliage reports, which debut this year on Sept. 26, “I think we are shaping up for a great season, with a big assist to some much-needed August rainfall, which helped with leaf retention.”

Like the leaves, however, all this is subject to change. The weather in the next four or five weeks will be critical, and don’t be fooled by their apparent stoical homogeneity: Those trees have complicated inner lives.

All things being equal — and how often does that happen? — those first flecks of color decorating the trees will begin filtering south as the trees take the hint that the sun’s powers also are heading south.

As the light intensity diminishes, the green chlorophyll recedes from leaves, yielding to the more flamboyant red anthocyanins, and the carrot-colored carotenoids, and the corn-like yellows.

The waves of color will ripple northeast to southwest, cresting in Vermont’s Green Mountains the first and second weeks in October. The peak waves then will spread to the Berkshires of Massachusetts and the Catskills of southern New York and the Poconos, and eventually wash over the Philly region at the very end of October.

» READ MORE: Here are some of the best places to see foliage around Philly

Various websites purport to show timelines, but be aware that the periods of onset and peak can vary tremendously from year to year and among elevations.

This variability is evident in the chart kept for the last 50 years by Polly’s Pancakes in upstate New Hampshire tracking the leaf color timing. The beginning of the peak periods has varied from Sept. 21 to Oct. 10.

And none of this happens linearly. Before their leaves turn red, the maples do not necessarily work in concert with the oaks, which are prodigious suppliers of the golden and yellowish tints.

As University of Vermont forestry professor William Keeton has observed, “It’s this very delicate dance between a whole bunch of different factors.”

While neither drought nor overwatering appears to be an issue this season, the golden leaves of the red oaks that are plentiful in the Northeast might show some tarnish.

“The oaks are going to have a little bit of a down year,” said Salge. They are having a “mast year” — shedding huge amounts of acorns — in parts of the Northeast, including Pennsylvania, said Abrams.

“They’re having a reproductive fest this year,” said Salge. That’s to the delight of countless chipmunks and deer, but there’s a downside for leaf connoisseurs: “They aren’t putting as much energy into the lot of things that create good foliage.”

Where are their priorities?

And the most important factor would be the weather between now and mid-October. Foliage flourishes with sequences of cool nights and sunny days.

» READ MORE: Warmer falls are affecting the leaves and other things

“If we stay dry and cool, we could have a vivid season,” said Reed.

So far, so good.

The government’s Climate Prediction Center favors below-normal temperatures for October for the Philadelphia region. It isn’t picking favorites on rainfall for the month.

But it’s been a tough time for the outlooks. They called for above-normal August temperatures for the Philly region, and they ended up being mighty close to normal. And meteorologists are fretting over their warnings about a historically busy hurricane season that so far hasn’t come to fruition.

» READ MORE: Those long-term outlooks aren't necessarily perfect

On a more personal level, of course, weather can affect your travel plans. For example, Skyline Drive in western Virginia can be as stressful as it is magical on a day when you drive in and out of fog banks. So pay attention to forecasts.

For the north country, where the show begins, the NewEngland.com site has a handy graphic that shows average conditions for each day. Again, these are just averages.

For the rest of the nation, the people at Explore Fall in the Blue Ridge area say they have toned up their computer model and have begun issuing their forecasts for the season. You can look at the forecasts by state.

The smokymountains.com site posts outlooks for the entire country.

The aforementioned weekly Pennsylvania Department of Conservation and Natural Resources updates and forecasts, assembled from on-site reports from forestry officials, begin Sept. 26.

Regardless of the intensity of leaf color, it’s all but a certainty that the fall sunsets again will be the most spectacular of the year, when the last lights of day electrify whatever is left on the treetops.