What does it mean in weather forecasting when the weatherperson says “40% chance of rain”? What factors are being considered to come to this prediction?

Question

A lot of times on the news, the meteorologist says, “today there is a 40 percent chance of rain” or “80 percent chances of snow”. What factors go into making this decision?

In: 2

Answer 1

It means they are predicting that 40% of the area in which they’re discussing will be getting some rain. They watch weather patterns and use past data to make their best guess.