What's the percentage of this weather forecast?

What percentage of the weather forecast refers to the possibility of rainfall? From "Now, 2 1:00, 22:00, 23:00, 0:00", it is impossible to absolutely predict whether there is rainfall and temperature, but the probability of occurrence is 68%, and about 70% is correct.

This kind of weather forecast using probability has been used since 1966 in the United States, 1980 in Japan and 1995 in China. There is also a more elusive word-precipitation probability is often mentioned. Forecasters often broadcast on TV that the probability of precipitation today is 70%. This precipitation probability means that the probability of rain in a certain area is 70%.

Extended data

Forecasters predict the percentage of precipitation opportunities in a certain area and a certain period of time through sorting, analysis, judgment and discussion based on various meteorological data. This is only the "probability" of forecasting precipitation, and it cannot guarantee 100%.

In the next 36 hours (every 12 hours 1 period), there will be precipitation opportunities above 0. 1 cm in three periods, regardless of precipitation time and region.

When arranging activities, it will not rain, and make proper preparations for rain; The probability of forecasting precipitation is 60%, and the activities are mainly rainy, supplemented by no rain; The probability of forecasting precipitation is 80%, so be prepared for rain.