Park rangers at Deception Pass State Park have posted “danger” signs, warning people to stay off the rapidly melting ice at Pass and Cranberry lakes.

Jack Hartt, who manages Washington’s most visited state park, said it’s been about eight years since he’s seen the buildup of ice on the lakes that was present over the weekend.

Dozens of visitors were seen walking across the surface of Pass Lake Saturday. Hartt, who lives on the lake, even saw someone cross-country skiing on top of it.

Consistent, sub-freezing weather in recent weeks took a major shift Sunday when temperatures started to warm considerably. Temperatures reached the 50s Tuesday morning on North Whidbey, making a potentially treacherous situation on the lakes that much more dangerous.

Hartt said he recommends that no one attempt to step on to the ice.

“It is not illegal to be on a frozen lake,” Hartt wrote in an email. “It’s a Rockwell moment we rarely get around here. But falling through thin ice is a disaster no one wants to see.”

The cold air in Western Washington is gone for the foreseeable future, said Nic Loyd, a meteorologist with Washington State University’s AgWeatherNet.