Some things to try:
Make sure the recirc button is off, allowing outside dry air to circulate.
Run the A/C with recirc on and check under the car to make sure condensation is draining. Related: check the condensation drain outlet hose for debris/ice that could be clogging it- one symptom is a damp passenger side carpet (if you have all weather floor mats, you'll need to check underneath)
Snowy boots/coats can bring in a lot of moisture that will condense on cold windows- using the defrost/floor setting with A/C to dry out the car helps...
2005 Pontiac Vibe AWD - Platinum