It’s not a sure thing, but the Puget Sound area could get some snow this weekend.

A system of frigid air is blowing through British Columbia and bringing some moisture with it, resulting in a 20 percent to 50 percent chance of snow tonight through Monday, said Johnny Burg, a meteorologist with the National Weather Service in Seattle.

If it does snow, accumulation through Saturday is expected to be less than an inch.

“Certain places might get hit and certain places might not,” Burg said.

Sunday could bring greater amounts, Burg said, depending on if the system brings more moisture. Any snow on Sunday will likely come early and again late in the day, with slight warming and some rain in between, Burg said.

Temperatures are forecast to top out in the mid-30s during the day and drop to the upper 20s at night through the weekend.

Low temperatures are forecast to reach into the upper 30s by Monday evening, turning any snow to rain.

Still, with freezing temperatures lingering for a couple of more days, people are cautioned by police and fire officials to avoid walking onto icy ponds or lakes. While the ice may look thick enough to hold a person, it isn’t.

“The weather doesn’t get cold enough around here for the ice to get thick enough to support the weight of an adult or a child,” said Leslie Hynes, spokeswoman for Snohomish County Fire District 1.

Children are especially tempted to walk onto the ice and should be cautioned against it, said Shannon Sessions, spokeswoman for the Lynnwood Police Department.

In January 2007, Seth James, a 15-year-old sophomore at Mountlake Terrace High School, died after he fell through ice on Martha Lake. The incident occurred at night and rescue efforts were slowed by freezing conditions and darkness.

“We certainly don’t want to see another tragedy like that,” said Hynes, whose department responded to the emergency.

If someone does fall through ice, she said, it’s best not to try to go in after them.

Onlookers should call 911 and try to throw a rope, flotation device or something else to the person for them to hang onto, Hynes said.

“The best thing to do is to stay off the ice,” she said.

Bill Sheets: 425-339-3439; sheets@heraldnet.com.