Attic moisture and temperature
Attic moisture usually appears because of condensation. If you have high temperatures and high humidity in your attic then you may also have a problem with mold.
Attic temperature depends on the outside temperature and it also depends if your house is insulated.
You can test the temperature level using a couple of thermometers. Place them in separate places and then calculate the average. You do not want the temperature to be too high or too low.
You can buy equipment that can indicate the humidity in your house, but the bad part is that this equipment is far too expensive and the results need to be analyzed by a professional. You can check the humidity level by observing the windows and the objects in the attic. If water is running down the window or objects seem wet to the touch, then the humidity is far too high.
High humidity means greater chances for mold to grow. Proper ventilation will help maintaining a constant temperature in your attic. You can add more vents over the soffits.
In rare cases, the humidity level may be too low. You can test this by touching something metallic in the attic and see if you receive a jolt of static electricity. If you do, then it means that the attic is too dry.