The colored bars on the 4-Color LCD Weather Station are graphic indicators for barometric pressure. The bar graph represents the air pressure (barometric pressure) of the past 12 hours and indicates from the right (going left): present, one hour, three hours, six hours, and 12 hours. Three illuminated bars is a normal level for the air pressure. Fewer or greater than three mean more or less air pressure than normal.
If more bars are lit than on a previous day, then the barometric (air) pressure has increased. The red/blue bars indicate pressure rising (bars higher in the scale) and falling. This is only a rough idea of the air pressure trend and also the small box right under the time shows a general trend of pressure. These indicators are about 70% accurate. The bar pressure graph flashes as the barometer sensor is reading data.