Please no fires until spring
This is a pretty concerning photograph. If the water in this fire hydrant is frozen, you can bet all hydrants connected to the same waterline are full of ice as well. This means that if any building in the area catches fire, their best hope is to wait for snow to extinguish it. And there’d have to be a lot of snow for that to happen.
Water in motion doesn’t typically freeze since the entire body of water has to reach 32 degrees F before ice crystals form. To make matters worse, since water expands when it freezes, the underground pipes probably need a good fixing when the ice thaws.