A sustained period of freezing temperatures jump-started Minnesota’s ice fishing season this year, but the weekend deaths of two fishermen northwest of Little Falls underscored observations from around the state that ice conditions are tricky.

“You really still have to be cautious,’’ Tim Sonenstahl of Wayzata Bait & Tackle said.

He said Tuesday that Lake Minnetonka’s deepest areas are now frozen, but ice thickness across some of those large surfaces is inconsistent and too thin in some areas to travel by foot. Some areas have only recently hardened after being kept open by flocks of ducks. Covered with snow, they now look no different than ice that is safe to walk on, he said.

Sonenstahl said Minnetonka’s ice is 7 to 8 inches thick on small bays like Black Lake and Seton Lake. Carson Bay, larger and popular for fishing, was covered Tuesday by 4 to 7 inches, he said. The good news for anglers is that the ice is getting thicker by the day, he said.

Still, conservation officers for the Department of Natural Resources (DNR) noted inconsistent ice conditions in weekly logs filed Monday.

As of Monday on Lake of the Woods, many ice roads were still not open to full-sized vehicles. DNR officer Eric Benjamin of Warroad said ATVs and snowmobiles were in widespread use and few anglers were having trouble catching their limits.

In the Bemidji area, conservation officer Brice Vollbrecht used his weekly report to caution anglers about greatly varying ice depths. A similar message went out from conservation officer Mitch Lawler in Alexandria.

“ATVs and small vehicles are common on smaller lakes but caution should still be taken,’’ Lawler wrote. “Ice thickness is variable around the area and more is needed before full-sized vehicles will be safe.’’

Ice on Cass Lake in northern Minnesota continues to thicken, reported conservation officer Mark Mathy. But anglers taking full-sized vehicles on the ice “are taking a big risk,’’ he wrote.

Sean Williams, the DNR’s officer in Ely, said in his report that ice conditions varied greatly.

“Some anglers reported as much as 11 inches and as little as 4 inches on the same lake,’’ he wrote.

Similar write-ups came from metro area conservation officers Luke Gutzwiller, White Bear Lake, and Tim Maass, Osseo.

“Anglers found ice conditions to vary, limiting areas which could be traveled by foot until ice conditions improve,’’ Gutzwiller wrote. Maass said anglers he checked were reporting “very inconsistent ice thickness.’’

The weekend ice fishing tragedy on Fish Trap Lake in north-central Minnesota took the lives of Wayne Vaverek, 68, and Leonard Sanoski, 71. They went fishing together Sunday, and family members alerted authorities after they failed to return home.

A search headed by the Morrison County Sheriff’s Department ended with the recovery of the missing men, one of whom was found on the bottom of the lake in the enclosed cab of a side-by-side ATV.