A mid-January thaw is melting a lot of snow in Iowa, but it’s also creating a lot of potholes on the roadways.

When it warms up during the day, the snow melts and the water seeps in cracks in the streets. At night, the water freezes and expands, creating potholes.

Cedar Rapids sent crews out this week to start patching the potholes. The city uses portable heating equipment to warm the asphalt repair mix to make the fix last longer.

Maintenance Supervisor Craig Hanson said he doesn’t know what kind of pothole season to expect because there has to be a full thaw to see the extent of the problem.

Des Moines is also working on its pothole problem. Public Works Director Bill Stowe said he expects potholes will get worse into March.