The weather was blue when Apple's mobile phone was turned on.

The weather shows blue as a low-level warning.

Forecasts are classified according to the severity and urgency of disasters. Blue is the lowest level of early warning and represents the average level of disasters. Early warning refers to the act of sending an emergency signal to the relevant departments to report the dangerous situation according to the laws summarized in the past or possible precursors observed before disasters or disasters and other dangers that need to be guarded against, so as to avoid disasters without knowing or preparing adequately and minimize the losses caused by disasters.

The weather symbol is a simple weather symbol, which is used to represent the current weather phenomenon. Common weather symbols include rain, sunshine and fog. The weather represented by weather symbols is graphically represented.