Larger crowds lead to more chaotic parking and drop-off situations and longer wait times at security checkpoints. Plan accordingly. In general, airports are most crowded on Monday mornings and Friday afternoons, as these days bear the brunt of business travel. Expect Fridays to get even busier in the summer months as recreational travel peaks. You’ll find the biggest crowds of the year on Thanksgiving Eve as well as the Sunday after it. And unsurprisingly, the busiest week to fly is the one that falls between Christmas .