What do the three grades of yellow, red and blue in the weather forecast mean?

According to the severity and urgency of the disaster (general, heavy, serious and particularly serious), early warning is issued with blue, yellow, orange and red icons in turn. Disastrous weather is divided into 9 categories, including rainstorm, high temperature, cold wave, fog, thunderstorm and gale, gale, hail, disaster and road icing. Previously, Shanghai, Fujian, Qinghai, Zhejiang and other provinces and cities have used this method to forecast disaster weather.