Some portions of the Northeast have a chance at vibrant fall foliage based on forecast weather, while drought-stricken parts of the country may not have much of a display.

Warm and wet weather through the remainder of September and into the first couple of weeks of October would not be good news for leaf-peepers in the Northeast, according to Dr. Marc Abrams, a professor of Forest Ecology and Physiology at Penn State. Abrams began observing how weather conditions affect fall foliage 25 years ago.

A late and muted peak in fall colors would be expected if warmth continues into the second week of October.

Instead, Abrams added, ideal weather for a colorful fall would be drier weather through the second half of September with colder temperatures, dipping into the 30s at night.

"A frost helps to bring out the color. What happens is that the chlorophyll - which causes the green color of leaves - starts to break down. This basically exposes the other pigments like red and orange," Abrams said. On the other hand, persistent warm and wet weather would extend the growing season, causing leaves to stay green.

A frost and freeze is most likely for upstate New York and north-central portions of New England during late September, according to AccuWeather Lead Long-Range Forecaster Paul Pastelok. This region will have the best chance for a bright and colorful fall.

While nights can get cool farther south and west, temperatures are not predicted to get cold enough to produce a frost by late September, Pastelok added. For the big cities along the I-95, including New York City to Washington, D.C., the central Appalachians and Ohio Valley, the mild weather may mean a late peak of fall foliage with subdued colors.

While warm, wet weather limits the bright color display of leaves, the opposite - abnormally dry conditions - can also have a negative impact. Drought conditions can impact the leaf size, vigor and physiology, and exceptional droughts can even kill trees.

Hard-hit drought areas of the Midwest and Plains, especially Iowa, Nebraska and Missouri, are probably not going to have a good display of fall foliage this year, Abrams said.

Extreme to exceptional drought conditions are gripping much of the nation's heartland.