DULUTH -- Last year on this date, anglers were walking onto the frozen surface of Lake Superior off Duluth and catching lake trout, herring and eelpout from holes drilled through about 6 inches of solid ice.

This year? Not yet. And it’s not looking likely. In fact, it's been so warm that there are anglers out in boats trolling on the big lake.

So far, the Great Lakes are mostly ice-free thanks to mild temperatures across much of the region. As of mid-week, only 6.5% of the surface of all five Great Lakes had any ice on them, about one-third of the normal ice for this point of winter.

Lake Superior is just under 7% ice-covered compared to 37% last year at this time and 50% in 2018, according to the Great Lakes Environmental Research Laboratory branch of the National Oceanic and Atmospheric Administration.

An unusually warm and windy January set the stage for all the open water. Duluth saw January temperatures nearly 6 degrees warmer than normal, a considerable departure from the 30-year average. Duluth’s January saw more days with highs in the 30s above zero — six — than days where temperatures dropped at all below zero — just five.

The only “fast,” or solid, ice on Lake Superior is in more protected areas like Chequamegon Bay and Thunder Bay. But even in those areas, there’s far less ice cover than normal. The Madeline Island Ferry continues to run from Bayfield to the island and could operate all winter without shutting down. That’s only happened four times in 150 years of ferry operations, all of those since 1998.

So far this winter Lake Superior peaked at about 10% ice cover, which would be the second-lowest peak since accurate records have been kept starting in 1973. The record low-ice year was in 2011-12, when the big lake peaked at just 8.6% ice cover.

All of the ice cover percentages are estimates made by experts based on satellite-based temperature data and are never 100% accurate.

The lack of ice has again prevented any access to the Lake Superior ice caves near Bayfield in the Apostle Islands National Lakeshore. There hasn’t been safe ice to the caves since 2015. On the other hand, if the low-ice winter continues, it should make for an easy breakout for the Great Lakes shipping industry which will awaken from its winter slumber just ahead of the Soo Locks opening on March 25.

While January saw far above normal temperatures (nationally it was the fifth warmest January on record) the forecast so far for February is cooler, with closer to normal temperatures. It only takes a few cold, still nights for some ice to form off Duluth’s western tip of Lake Superior, as it did Thursday.

But the later we go without much ice, the harder it gets for ice to form. As the days get longer and the sun gets higher in the sky, it has more power to melt ice, even on sub-freezing days. And there are still no arctic outbreaks in the near-term forecast to plunge the Northland far below zero.