DC is still ticketing cars despite the meters being buried under snow.
Looking at it through the Common Law angle, the city is entitled to charge for parking whether the snow is there or not, although it is a dick thing to do. On the other hand, those who have shoveled their asses off because the city can't seem to clear the streets definitely have a claim to get that ticket money refunded.
Overall, those who live and thrive in the city ultimately agreed to this mess. It's Commerce.