I'd find a relatively steep hill nearby or flight of steps and run them up and down outside despite the weather. If they're exercising hard they won't be bothered by the cold for a few minutes, and a steep hill or staircase run pretty much poops them out after only a few minutes as long as you keep them going.
What size dogs are these? If they're fairly small you can just play fetch with them and keep them running up and down a hallway or the longest stretch of the biggest room. You could probably even do that with a larger sized dog as long as you get a good rhythm going and can keep them continually running. Takes a lot longer to poop them out without an uphill grade though.
Other than that, if you have some extra money you might want to look into buying a good used treadmill for them to use. Man, it's a shame you don't live near me. The fitness center next door is always throwing out perfectly usable equipment and replacing them with new stuff instead of just fixing something minor like a tear in the seat of a stationary bike or little things like that. Every couple of months or so some good piece of equipment gets pitched next to one of their trash dumpsters out back to be thrown away. Just recently they threw away a nice sofa they must have had in a lounge area but before anyone could snag it it got rained and snowed on. A month or two before that they threw away a perfectly good rowing machine that one of my neighbor's snagged and has it in his basement to use. He's still beside himself with glee for that great find, and all it needed was a couple of squirts of oil here and there. Several of the neighbors are waiting for the next stair stepper to get pitched out... there's going to be a mad race to see who nabs that one. LOL!
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