Waze assumes you are travelling in the direction you were last driving when you shut the app down.
If you drove home heading north, Waze will route you driving north the next time you start going (and vice versa). If you start driving south Waze should recalculate or you can do what I do, start driving in the correct direction, let Waze realize it, then start navigation.
If the above doesn't apply, please post a
Permalink so we can look at the area.