On the chilly first day of March, ice covering the Lower St. Croix River gives off ghostly sounds, as if the water beneath was gasping for breath.

The mighty river, just a few weeks away from ice-out, is now approaching that dangerous time of year when its strong current drives unfathomable tons of ice downstream.

"Use caution," Stillwater ice sailor Kent Nord said last week. "All bodies of water should be respected."

The St. Croix's ice-out is a seasonal milestone, a beckoning to those thousands of boaters who wait eagerly for the spring thaw. So do the paddlers, who have waited since autumn to launch canoes and kayaks in the quieter waters north of Stillwater.

One of them is Greg Seitz, who writes a blog titled St. Croix 360.

"That first warm day gets me dreaming, and then it's just a painful wait," he said last week after exploring ice conditions at Marine on St. Croix and Scandia.

"After our false start on spring, all the snow is gone from the surface, which will help because it won't insulate the ice. The ice is clear and dark, refrozen after being quite soft — nowhere safe for walking."

Farther downstream at Bayport, where Nord was sailing on the frozen river at speeds of up to 60 miles per hour, the ice was at least a foot thick. He wasn't concerned about falling through — he grew up on the river and has ice-sailed for about six years — but he said he planned to spend just one more day on the ice this season.

He, too, heeded the warning that comes with black ice.

"In the fall, black ice is good. In the spring, black ice is bad. It gets really dark, almost spooky like a storm," said Nord, who stowed his 200-pound sailing craft as geese honked over the St. Croix.

As for his glide across the river, the ice was rough, he said.

"It's like a coffin," he said of his boat. "You lay inside that thing and hang on for dear life and pay attention."

Farther down the St. Croix, near the Interstate 94 bridge, the frigid blue river was running free of ice. It was there a year ago that a 45-year-old man drifted downstream on a patch of ice that broke loose near Hudson, Wis.

Firefighters and sheriff deputies rescued him from the river, which registered a mere 33 degrees at the time.

But even that open stretch disappears about a mile farther south at Lake St. Croix Beach, where sounds of cracking ice echoed over the valley last week.

On the stretch of river north of Stillwater that paddlers favor, the ice needs just a few warm sunny days to break up, Seitz said. That should happen this week, when temperatures are forecast to rise into the 60s.

"Not much is going to melt today," he said Wednesday, when the temperature was 32 and the north wind whipped over the ice. "There were several narrow slivers of open water and big slabs of ice askew in the middle."

At Log House Landing in Scandia, where many paddlers continue to launch into October, Seitz was surprised to see a partly opened channel on the Minnesota side of the river.

"I had the predictable stupid moment of wondering if I could get a kayak in it," he said.

Kevin Giles • 651-925-5037