Fresno arborist Susan Stiltz was driving in northwest Fresno recently when she noticed a tall tupelo starting to change color, and one thought crossed her mind: The first sign of fall.

It’s when trees, bushes and vines become canvases of yellows, oranges, reds and rusts.

In other words: time for a road trip. But where to go? A Web site, californiafallcolor.com, makes it easy to track where color is changing. The site features photos and blogs from 56 contributors, called “color spotters.”

John Poimiroo, Webmaster and blogger for californiafall color.com, says the site is designed to help people plan trips from simple family outings to serious backpacking adventures.

The site gives popular areas a “reading” that estimates the percentage of color change. A reading of 15-30%, for example, suggests travelers can wait another week. Perfection is 75-100%.

In the eastern Sierra, Crowley Lake, a popular fishing lake in Mono County, has a current 15-30% reading and shows “light green to yellow” aspens lining the canyons.

The color change works its way down about 1,000 feet in elevation per week; this week leaves were changing at about 7,500 feet.

Yosemite National Park’s floor, at about 5,000 feet, should turn spectacular before month’s end.

“In Yosemite Valley, one of the treasures is the black oak, with its blacks and yellows,” Poimiroo says. “Yosemite Chapel is surrounded by fall leaves; it’s the classic photo.”

It appears eastern Madera County towns, such as Oakhurst, have another month or so. Then comes Fresno and its surrounding farming communities.

“All the vineyards have a lot of fall color in them,” Poimiroo says. “You have so many barns around Fresno — and they’re beautiful with the colors.”

The reporter can be reached at rorozco@fresnobee.com or (559) 441-6304.