Humidity issues

So I'm just starting out and while my seeds are germinating I've been trying to improve my greenhouse environment. This morning i noticed i had a temp of 66° and 85RH.

To give a little context, on one side of the greenhouse i have a 20 inch box fan blowing air in from a almost ground level window, on the other side i have an 8 inch exhaust fan on a thermostat and a 3' x 2' window next to it.

of course my concern is the RH is too high, I'm thinking of closing the ground level window, moving the box fan in a place so it still pushes air around and add an exhaust fan in the window next to the 8 inch exhaust fan.

However it did rain last night and i'm now thinking i was pulling in moisture from outside.

If that doesn't work, what would you think the next step is in lowering the RH.??

Moving to a drier climate. Trying to control atmospheric conditions in a greenhouse is hard except for heating. Sealing would be necessary with incoming air dehumidified

Well mid day and with the lower ground window closed some, I’m 79 degree with 63RH. Now I’m thinking during rain and at nights i should close all openings.