There is nothing more dangerous than driving without being able to see. Ideally, getting an engine up to operating temperature in any weather minimize this. It may sound silly in the summer, but if the window is fogging up, it's most likely due to the fact you're using the air conditioner. When the two different temperatures collide; the outside temperature and the temperature of the inside of the windshield, the result is fogging.
Allow the vehicle to warm up to running temperature . Compare the outside temperature and realize that the temperature of the inside of the windshield will need to match that or slowly change to compatibility with it.
Place the air direction onto defrost on your climate control panel and turn the air on high. The more air striking the windshield, the quicker it will defog. If it's extremely cold out, crack the side windows on the doors or pivot windows to allow an air vent until the interior temperature has become adapted to the outside air.
Turn the heat index on your climate control panel upward to accommodate changing temperatures outside. If it's a warm, muggy day and you have on the air conditioning, but suddenly drive into a thunder storm where the temperature drops drastically, it's going to affect the windshield and windows. Even with the air conditioner running, you can adjust the heat index upward to adapt to the temperature change outside and prevent the windows from fogging up.
Buy and install vent visors for your vehicle as these will allow you to roll or crack your side windows down and prevent the weather elements (other than air) from getting into the cab of the vehicle.
