A more thorough explanation:

The natural-accumulation doctrine is a rule that states that a government or landowner is not obligated to remove naturally occurring ice or snow from public property, such as a highway, unless the entity has taken some affirmative action that has increased the danger to the public.

For example, if a city builds a highway that causes snow to accumulate in a way that creates a hazard for drivers, the city may be responsible for removing the snow. However, if the snow is simply a result of natural weather patterns, the city is not required to remove it.

This doctrine is based on the idea that it is unreasonable to expect a government or landowner to constantly monitor and remove natural hazards that occur on their property. It also recognizes that some hazards are simply a part of living in certain climates and that individuals must take responsibility for their own safety when traveling in these areas.