There are two main highways that go Flagstaff: I from Phoenix and the I, which is most often taken from Las Vegas.
Both of these highways can have regular traffic and road condition issues year-round. Use your everyday apps like Google Maps and Waze to get a good idea of your travel time. But you can use the Arizona Department of Transportation website to get more details regarding road closures, construction and weather conditions. You can count on traffic starting on the I as far south as Black Canyon City if you leave on a Saturday after 9am on a 3-day weekend. We recommend that you travel north on a Friday night after 7pm or before 9am on Saturday.
That's your best window, otherwise, traffic is often bumper to bumper and can add hours to your time on the road. There is often bumper-to-bumper traffic when there is an accident or construction on this highway, which unfortunately happens pretty often - especially in inclement weather.
Make sure to check road conditions and traffic reports prior to embarking on your journey. I has a couple not so great features that are good to know about.
First, there are a lot of potholes. Second, I gets extremely slick during winter storm conditions in the stretch of highway between Flagstaff and Ashfork.
