Valleys are Cool!

Topography of the Tristate with the pre-glacial course of the Ohio River. Cold air drains into the valleys and they are often colded and  frostier in the morning.

Cincinnati and the surrounding countryside north of the Ohio river is a region of valleys, not really hills. The last glacier this far south reached the present day position of the Ohio River and the loose sediment  bulldozed ahead of the wall of ice filled old valleys and mostly leveled things out.

The Ohio River before the glacier followed the white arrows across Norwood, north into Butler County then southwest along what is now partly the Great Miami River Valley and partly the White Water River Valley.

The fairly loose material eroded into today's steep sided stream valleys of the modern tristate.  South of current Ohio River the landscape was left untouched by the glacier and the hill sides in Kentucky are steeper and the valleys deeper.

Now to get to the weather part of this post cold air drains into the those valleys and often they are much colder than the uplands.  In fact it is not uncommon to have temperatures in Morrow, OH along the Little Miami River 20° colder than the level areas high above the valley.

That leads to earlier frosts, more frequent fogs and sometimes icy weather in the valley when higher elevations are above freezing and getting rain.

There is more in the video.