Weaving across the road or drifting from one side to another. Open window in cold weather. Speeds up or slows down suddenly, driving too fast or too slow. Be alert for drunk drivers and sleepy drivers late at night. As a Clue.
Drivers look in the direction they are going to turn.
You may sometimes get a clue from a driver's head and body movements that a driver may be going to make a turn even though the turn signals aren't on. These clues are most easily seen in motorcyclists and bicyclists. Watch other road users and try to tell whether they might do something hazardous. Other situations include slow moving or stalled traffic in a traffic lane, and accident scenes. Watch for other drivers who are in conflict because they are a hazard to you.