Cleveland is a year-round running town. Cuyahoga County (Cleveland and immediate suburbs) is the county with the most races in Ohio.
Here is a convenient link to an always-current list of upcoming races in Cuyahoga County. I like the exhaustive nature of Running in the USA, but the searching is a little awkward sometimes. This should take care of that.
There are still four in December and five in January and February, the worst months to find a race in the area.