The National Weather Service has issued a winter storm watch for Monday and Tuesday as the second of two weather systems arrived in the area.

Five to 10 inches of snow is possible at 9,000 feet elevation in the northwest and southwest San Juan Mountains, the weather service said Monday. Winds could reach gusts of 50 mph.

Residents of Montezuma and La Plata counties face a 70% to 80% chance of rain Monday night and a 90% chance of rain or snow Tuesday.

A weather service freeze warning, issued Sunday for Southwest Colorado, expired 10 a.m. Monday. According to the weather service, temperatures hit a low of 29 degrees about 6:50 a.m. Monday in Cortez and 32 degrees about 5:50 a.m. in Durango.

The weather service upgraded its forecast Monday morning from a winter storm watch to a winter storm advisory. A watch is issued when the risk of a storm has increased, but an advisory indicates the storm is imminent or likely.

Subfreezing temperatures are expected alll week in the Four Corners area and in the Upper Dolores River Basin and the Animas and San Juan basins.

Temperatures could drop into the mid-20s Tuesday through Friday, the weather service office in Grand Junction said.

High temperatures are expected to fall from around 60 degrees Monday to the mid-40s on Tuesday before rising to about 50 degrees Thursday and 60 on Sunday.

The first weather system blew in Friday, said meteorologist Scott Stearns. The second system arrived late Monday.

“I think most of the precipitation from that second system should be ending Wednesday morning,” Stearns said.

The unseasonably cold weather also will speed the foliage color change in Southwest Colorado. As of Monday morning, the San Juan National Forest’s fall color report was as follows:

Nicholas Johnson of The Durango Herald contributed to this article.