Exterior condensation on windows occurs primarily in the morning when days are warm and humid, but nights are cool. It usually clears as the day warms. Exterior condensation can occur at any time, especially in warm, humid climates where interior temperatures are cooler than outdoor conditions. When you see exterior condensation, it means the windows are doing their job. However, if you find a lot of condensation on the inside of your windows, check your inside humidity, you don't want this to get out of hand.

The presence of moisture indicates that specific sets of atmospheric conditions exist, and the insulating glass is doing its job. In this case, that insulation capability is what retards the flow of building heat through the glass and prevents warming of the exterior above the dew point.

If exterior condensation occurs on insulated glass, there is little or nothing that can be done to prevent its reoccurrence. Draperies should be open to allow as much heat transfer though the glass as possible. Trees or buildings can block the radiation view to the sky. Since you have those large trees close to the house, that explains some of the issue. Shrubbery immediately adjacent to the glass can increase the local humidity and may need to be moved. The exterior surface of the glass will warm and the condensation will evaporate when the heat loss to the sky is blocked, the wind picks up, or sunlight is absorbed on the glass surface.

If the house is staying cooler in the summer it sounds like it's well insulated. The lower level is probably what keeps the temp down. Since it's below ground it stays cooler than the upper level. I would feel safe to say your house is just fine. If your getting moisture on the inside or it smells musty or like mildew, you may want to search it out. Otherwise I think your fine. Good Luck!!!