How do air pressure and precipitation determine the weather in a certain area? When the air pressure is higher, the air is cooler, and it is less likely for precipitation to fall. When the air pressure is lower, it is harder for evaporation to occur and for the rain to form. When the air pressure is higher, the humidity is higher, and the chance of precipitation is lower. When the air pressure is higher, the air is warmer, and the chance of precipitation is higher.