Understanding a 30% chance of rain in weather reports

A weather report stating a 30% chance of rain means there is a 30% probability of receiving at least 0.01 inch of precipitation at a specific location. It does not indicate how long it will rain or how widespread the rain will be. The concept of probability of precipitation (POP) was introduced in the U.S. in 1965. Forecasts now rely on multiple weather models that simulate different scenarios to predict precipitation. A 30% POP suggests that three out of ten models indicate rain. Modern forecasting uses data from satellites, radar, and weather balloons to improve accuracy. Despite advancements, forecasts can change due to the unpredictable nature of the atmosphere.