A report of ice on a Cotati area on-ramp and colder than expected morning temperatures suggest motorists should be alert to slippery conditions Friday morning, the CHP said.

Overnight fog likely left enough moisture on the pavement in some areas to cause icy conditions, CHP Officer Steve Fricke said. There also were reports of at least two vehicles spinning out, including one on Magnolia Avenue in north Petaluma.

"You gotta remember, once we get down into the low 30s, it doesn't take much for ice to form," Fricke said.

Though temperatures are forecast to inch upward in the next several days, Friday morning lows remained very cold, with 26 degrees recorded at the Charles M. Schulz-Sonoma County Airport - several degrees lower than had been expected.

"I think they were expecting the high clouds to linger longer this morning to keep the relatively warmer air over the region," meteorologist Steve Anderson said. "But the high clouds abruptly moved out of the area just in time for cooling to occur."