I keep the outdoor temperature sensor on the kitchen window sill, sealed in a baggie to protect its electronics from rain and dew. Apparently the wind from Saturday night's norther blew it off the window sill and it fell in the dogs' water bowl, where it froze solid as temperatures dropped into the 20's. I took a picture before chopping it loose this morning, but I guess I didn't save it. I think you can get the idea from the hole in the ice and the still-trapped baggie.
The baggie did its job, though, as the sensor bravely reported a temperature of 21 degrees at the bottom of the frozen water bowl before I rescued it.
Never underestimate the power of a baggie.