There is a 70% probability that Eastern North-American tree leaves contain ANTHOCYANIN, the pigment responsible for the red or brown autumn colouration. The combination of cool weather and reduced day light allows the warm pigment to emerge.
Head to weather.com and search "Fall foliage" to discover the peak leaf-viewing days in your area. (or click here).
The New York City and Long Island area is Near its Peak (50-75% change) depending on your area, but you don't need a website to tell you that. Go enjoy the scenery for yourself.
To read more about Fall and how great it is, read my Fall Colours post from last year.
1. Tanenbaum, Sharon. "The Simple List." Real Simple Oct. 2010: 14.
2. Palm, Carl E. . "Why leaves Change Colour." Fall Foliage. . SUNY College of Environmental Science and Forestry. 14 Oct. 2010