An unseasonably warm December wasn't doing any favors for east-metro ice fishing enthusiasts, a group of folks often willing to hit the ice after only a few days of freezing temperatures. Weeks of warm weather meant lots of open water and few fish houses in Washington County.

Until Christmas week, that is.

While state and local officials caution that no ice should be considered totally safe, a blast of arctic air in the days leading up to Christmas was probably enough to get anglers back on Washington County ice in search of fish.

And rising temperatures in the mid-20s, with lows in the single digits, may mean a better and safer platform for ice fishing, said Pete Boulay, a climatologist with the state Department of Natural Resources (DNR). But he won't guarantee it.

"We are never going to say, 'OK, now the ice is safe,' " Boulay said last week. "It all depends on the forecast, whether there's a storm or not, whether it's cold or not.

"What we need for good ice formation is the lack of snow cover on the ice and preferably nights below zero."

It certainly wasn't looking hopeful during the couple weeks before Christmas. Several days of temperatures that climbed into the 40s chased people off what little ice there was on Lake Elmo, Big Marine Lake and White Bear Lake, and for good reason, said Lisa Dugan, recreation safety outreach coordinator for the DNR.

Dugan stressed that anyone venturing out on the ice should be prepared, not only by carrying something to help pull yourself out of the water — such as a couple screwdrivers or long nails — but also by wearing a life jacket whether you're "on foot, on a snowmobile or an [all-terrain vehicle]."

Ice on rivers, such as the St. Croix, can be especially tricky. Two weeks ago, she said, the rivers were completely ice-free.

"A lot of counties are warning people to not even go out on foot because of weather fluctuations," she said.

The DNR says ice thickness must reach 4 inches before it is safe for walking or ice fishing, 5 to 7 inches to support a snowmobile or all-terrain vehicle (ATV), 8 to 12 inches for a car or small pickup and 12 to 15 inches for a medium-size truck.

The best way to tell if ice is safe is to drill it with an auger or chip it with an ice pick, then use a measuring tape to get an accurate depth.

It's best to check every 150 feet as depths can change from point to point, Dugan said. Or, she added, you can ask people coming off the lake where the trouble spots are. Asking about ice conditions at a local bait shop or lakeside resort is a good step too, she said.

Five people have died in Minnesota after crashing through the ice so far this winter, she said. That compares to two statewide fatalities for the entire previous winter season and none the year before that, Dugan said. All five fatalities this season were people going through the ice on snowmobiles or ATVs.

Jake Willis, state conservation officer for the DNR's Maplewood Station, said the cold snap that started just before Christmas certainly helped. But the watchword continues to be caution.

"For me, personally, I want a solid week of 20s," he said. "But it's not just air temperature. The effect of [ultraviolet] rays, the sun beating down, also can make the ice inconsistent. On a sunny day, it may be 30, but it feels like 35 or 38."

Even though it's likely that last week's frigid temperatures thickened the ice, Willis advised eager folks to "hold your horses. There's no fish worth going under the ice for."

Dugan agreed. "You will never regret waiting a little bit longer," she said.