It sounds like your windows are subject to the dew point. Without looking at your home several variables could exist and should be checked by an energy rater or a building analyst.
- What type of windows do you have? Double pane, low-E SHGC .30 or better would help.
- Does the home have good insulation? R-38 would help in the attic with an ACH less than 5 on the blower door test.
- What is the age and condition of the HVAC (AC) system? Check the duct work for leaks.
Mold growing in your home is a big concern. Please have your home checked--- comfort, health, or high energy usage could also be related.
For more information:
Read "Our aluminum-frame windows are harboring condensation and mold. Can you recommend window solutions for a damp environment?" a Q&A answered by Steve Saunders.