Whether to commence or continue play in a round when fog is present is a difficult decision. Fog, by its very nature, is not easy to forecast, and it is challenging to predict when it will set in or lift.  

From a playability standpoint, it is the USGA’s policy to commence/continue play in a round if the landing zones for all shots to be played are visible to the players. In this regard, tee shots requiring the use of a driver may present the most difficult challenge since such shots cover the most distance.  

Things such as fairway lines, bunkers, penalty areas, trees, etc., in the drive zone must largely be visible.  

However, the fact that visibility is partially obscured by fog such that the entire flight of the ball is not possible does not generally require a decision to delay/suspend play.  

Generally, the Championship Director will seek the assistance of Rovers in determining the playability of the course. If you are asked for information about an area of the course, communicate that clearly and concisely.  

In the case of any suspension where a championship utilizes two courses (e.g. U.S. Amateur), typically the goal is to try to treat the courses the same with regard to suspensions and resumptions (when one course suspends, the other does at the same time, and vice versa). Ultimately this determination will be made by the Championship Director and depend on the proximity of the two courses, current and future weather patterns and their timing as well as the overall impact on key stakeholders (i.e. players, host venue, broadcast, etc.) involved with the championship.