Leaves are starting to turn in Pennsylvania. When will fall foliage peak in your area?

Believe it or not, autumn has arrived after an eventful summer season. For Pennsylvania and much of the northeast U.S., that means colorful fall foliage is just a few days or weeks away.

The Pennsylvania Department of Conservation and Natural Resources says leaves are just starting to change colors across most of the commonwealth as September nears its end. Some counties in northwestern and southwestern Pennsylvania are already approaching their best colors , according to the agency’s latest report, but most of the commonwealth still needs to wait for local foliage to hit its stride.

Some parts of Pennsylvania might observe more limited fall foliage this season due to abnormally dry or drought conditions , according to the U.S. Forest Service. Abnormally warm temperatures throughout the fall can also lower the intensity of autumnal hues, which may pose a problem for parts of Pennsylvania and the northeast at large.

Here’s what you need to know about Pennsylvania’s fall foliage outlook this year.

Pennsylvania’s 2024 fall foliage outlook

If you’re excited for leaf-peeping season, you still have plenty of time to prepare for autumn’s best colors.

According to the season’s first fall foliage report out of the DCNR, leaves across most of Pennsylvania are just starting to change. The forecast, which covers Sept. 26 through Oct. 2, suggests leaves are already approaching their best colors in just three counties — Pike, Somerset and Wayne — but have not started changing in Philadelphia and its suburbs in Bucks, Chester, Delaware, Lancaster and Montgomery counties.

“After several periods of dryness during the growing season, much-needed summer/early fall rains helped stave off premature leaf drop, keeping forest canopies green,” the DCNR’s report reads. “Cold nights, coupled with prevailing dry conditions during late August and early September stimulated noticeable color changes throughout Penn’s Woods. Fall foliage viewers should expect a vibrant season that arrives sooner and last for a slightly shorter period compared to recent years.”

According to the DCNR, counties whose foliage is “starting to change” — the designation set for all but nine of Pennsylvania’s 67 counties — should expect peak foliage to arrive in about two or three weeks. The forecast suggests fall’s best colors should arrive in the second or third week of October.

Ranger reports included in the DCNR’s outlook suggest changes are starting in the Centre County area, notably near Bald Eagle State Forest and Rothrock State Forest. The forecast expects peak color to arrive in mid to late October.

The Farmers’ Almanac predicts fall colors will peak in Pennsylvania between Oct. 5 and 21. The Smoky Mountains Fall Foliage Prediction Map , generated annually using data from the National Oceanic and Atmospheric Administration, suggests fall colors will hit their stride between Oct. 14 and 21 for most of Pennsylvania.

Centre County offers plenty of great spots to view fall foliage, including nearby state forests and several driving routes such as Route 504, Benner Run Road and Tram Road. Black Moshannon State Park is a popular option, too.

Could drought and warm temperatures affect foliage?

Yes. According to the U.S. Forest Service, a late spring or severe summer drought can delay the onset of fall color by up to a few weeks. Additionally, warmer weather during the fall season can lower the intensity of observed autumnal colors.

Generally, the best conditions for bright and clear fall foliage are a warm and wet spring, favorable summer weather and warm, sunny fall days with cooler nights, the agency reports.

Recent models from the National Weather Service’s Climate Prediction Center suggest Pennsylvania is likely to observe above-normal temperatures between September and November . The eastern half of Pennsylvania is also more likely to observe above-normal precipitation in that span. Warm and wet weather this fall could affect fall foliage across the commonwealth.

Increased rainfall might be a welcome sight in some parts of Pennsylvania. As of Sept. 24, more than half of Pennsylvania is considered “abnormally dry” with some counties to the southwest experiencing severe or, in Greene County’s case, extreme drought, according to the U.S. Drought Monitor.

As of Sept. 26, State College has received 36.45 total inches of precipitation so far in 2024, according to NWS data. That mark sits well above the 31.41 inches expected over that period in an average year for the area.

Why do leaves change color each autumn?

While changing leaves presents a treat for the eyes, the color-changing process serves a far greater purpose.

The transition from lush greens to shades of yellow, orange and red represents one part of some tree species’ preparations for winter and colder weather. Chlorophyll, which gives leaves their green pigment and helps produce food through photosynthesis, is no longer produced in the fall as sunlight dwindles and temperatures drop. In chlorophyll’s absence, other natural compounds give leaves their new colors.

Some trees, including pines and other evergreens, are equipped with needle-like foliage that can resist freezing in the winter. Other trees with broader leaves must shed their foliage each winter to prevent leaves from freezing and ensure their survival .