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’s not that there is a 40% chance of rain. It’s 40% of the forecasted area will get rain, they just don’t know 100% sure where exactly. Obviously the further out the timeframe is then the less accurate the prediction.