This could well be the week that fall colors take off in much of Missouri, says a University of Missouri expert.

It’s the sugars in the tree leaves that create the gold, red and purple of fall, and the warm days and cool nights of recent weeks are crucial to the trees beginning to turn.

“That’s the perfect recipe,” said Hank Stelzer, a state forestry extension specialist and chair of the Foresty Department at the university.

Of course, colors change at different times across Missouri.

“It’ll tend to move from the northwest to the southeast part of the state,” he said. The peak might only last two or three weeks, he said, and he pointed out that some areas north and east of Kansas City are experiencing a flash drought, which can mute colors.

The Missouri Department of Conservation says colors usually peak in mid-October, and it posts weekly updates. Last Friday it said the Kansas City area is lagging and will peak later than normal this year. Rain would help.

“Dogwood and white ash are showing purples (in the metro area), and an occasional red or sugar maple is turning,” the department says at “Look for yellows to start showing on honey locust, elm, redbud, hickories, and hackberry.”

The department also predicts peak colors right now in northwest Missouri and says they are “just around the corner” in the central part of the state – Columbia, Jefferson City, Lake of the Ozarks. The sumac and Virginia creeper have started turning red in the southwest part of the state.

Frost plays a role, too, but Kansas City’s average first frost is Oct. 28, still two weeks off, though last year’s came on Oct. 6 and in 2011 it was Oct. 19. The average first reading of 28 degrees, generally considered a killing frost, is Nov. 6. The current National Weather Service forecast includes nothing below 42 for the next week.

Where to drive? Stelzer suggests Missouri 13 from Interstate 70 south the lakes region – but also says U.S. 24 is reliably good.

“I would say pay attention to the river route,” he said.