Why can smoke from a wildfire only be smelled at night?

There's a wildfire in AZ that has been burning since last week. I live almost 300 miles from where it started but the smoke and ashes hit us pretty quickly. During the day, the sky here is pretty clear and there's no smoke smell, just ashes flying around. About an hour before sunset, the smoke settles over the whole city again and the smell is very strong and comes in through the vents. Just wondering why it's smoky only at night.