The boating season unofficially opened at 1:46 p.m. Saturday as ice-out was declared on Lake Minnetonka, coming close to the normal time for ice-out despite the past winter's bizarre weather.

The Hennepin County Sheriff's Office Water Patrol and the Freshwater Society officially announced ice-out on the metro area's largest lake just one week past the lake's median ice-out date.

By the Water Patrol's definition, ice-out doesn't mean every crystal of ice has vanished from the water, but that a boat can safely maneuver through the lake's 37 bays and channels without frozen obstruction. With much of the lake having long since opened, boaters have already been out riding its waters.

Once the ice starts dissolving, it can happen fast, said Water Patrol spokesman Edgar Linares.

"It changes so dramatically in hours, so [Wednesday] we were seeing several inches of slush and ice, and if you look out on the bay now it's virtually gone," Linares said Thursday.

The 14,500-acre lake is typically the last one in the metro area to melt, which is why ice-out there is considered the opening signal for boating. Lake ice in southern Minnesota, with its slightly warmer temperatures and typically shallower lakes, melts sooner. Lakes north of the Twin Cities, where it's colder and waters are deeper, are still mostly frozen.

As of Saturday, a map maintained by Minnesota Department of Natural Resources (DNR) climatologists showed the northernmost lake without ice was Florence Lake near Cambridge. The DNR records dates submitted by area residents.

Lake Minnetonka opened up last year on May 5, tying 1857 for the latest date on record. The earliest recorded ice-out on Minnetonka was March 11 in 1878.

A snowstorm April 10 through 12, coupled with February's record-smashing snowfalls, made the past couple of months feel especially wintry this year. But snowfall doesn't delay ice-out; in fact, it warms the ice and can hasten it, Linares said.

"I think that the snowfall [last week] and the rain we had on Wednesday helped to get us this far," he said.

Wind also plays a part, especially on a big lake like Minnetonka, said Kenny Blumenfeld, a DNR climatologist.

"Wind does a really nice job of breaking up those sheets of ice and letting the waves have their way with them," he said.

Temperatures this year have been milder than last year's, Blumenfeld said. The earlier storm notwithstanding, April's temperatures have been about normal, he said.

In comparison, he said, "Last year, the first half of April was pretty cold, March had been cold, and it stayed cold for a few more days."