The weather forecast says that the probability of precipitation on a certain day is 90%.

Precipitation probability refers to today.

The probability of rain in this city is 90%.

This raises questions again. Why not say that the probability of rain is 100%? This is because scientists are only 90% sure whether it will rain. Probability is a mathematical term, and its intuitive meaning refers to the possibility of a thing happening. The prediction published in the form of probability is called probability prediction. If we are 90% sure whether it will rain, the weatherman will tell everyone that it will rain today.

The general situation of precipitation probability forecast is sunny, and the probability of 0% is impossible to precipitation; Sunny to cloudy, the probability of precipitation between 10% and 20% is very small; Cloudy, sporadic or local precipitation, when the probability is between 30% and 50%, there is a chance of precipitation; Precipitation, the probability is between 60% and 70%, and the possibility of precipitation is relatively large; When it is greater than or equal to 80%, the possibility of precipitation is high; If the probability is 100%, there will definitely be precipitation.