Regions of Ohio

Columbus sits in the middle of the state with no lake to moderate it and no hills to break anything up, which makes it the plainest severe-weather setup in Ohio: the spring squall lines arrive off the Indiana line with a clean run. Winter is the freezing-rain line, and it sets up over the metro more often than anywhere else in the state.

Lake Erie is shallow, which is why it runs the forecast here twice over: it is warm enough into December to load the snow bands that bury the east side and the snowbelt beyond it, and it freezes solid enough by February to shut them off. The same lake keeps the shore cooler than Akron all summer and later into autumn than the map suggests.

The Ohio River runs the forecast here. It cuts a valley deep enough to pond cold air under warm air aloft, which is why the winter line between rain and freezing rain so often falls across this corner of the state rather than north of it, and why the river towns hold fog after the hilltops have burned off. Summer works the same trench in reverse, trapping humidity until the valley is several degrees warmer than the plateau above it.

The ground starts rising here, and that is the whole story: the snowbelt that comes off Lake Erie runs out of lake but not out of lift, so the hills of Summit, Portage and Geauga wring out more snow than the shore does. Amish country to the south holds the cold in the valleys long after Akron has thawed.

Ashtabula County is the snowiest ground in Ohio and it is not close: the longest fetch on Lake Erie ends right there, and the hills behind it take what the lake gives. Youngstown sits far enough inland to miss the worst of it and gets the cold instead, and the river counties to the south run their own valley fog most of the autumn.

This was the Great Black Swamp, drained into the flattest farmland in Ohio, and it still behaves like a floodplain when the Maumee backs up. Flat and open means the wind has a clean run and the snow drifts rather than falls; it also means Lake Erie can push a foot of water into the western basin on a hard southwest blow and take it back out again.

The Miami Valley is Ohio's tornado corridor. The Memorial Day 2019 outbreak put fifteen tornadoes down across these counties in a night, and the 1974 Xenia tornado is still one of the worst in American history. The rivers that made the region flood it too — the 1913 flood is why Dayton built the dams it did.

The only part of Ohio the glaciers missed, and it shows in every forecast: narrow valleys that hold fog until noon, hollows that run ten degrees colder than the ridge above them, and creeks that come up fast because there is nowhere flat for the water to go. The Ohio River floods here on someone else's rain.