Pressure and Temperature
As we add heat energy to molecules, those molecules begin to move more rapidly. This causes those molecules to exert an increased pressure as they bump into objects around them. It would thus naturally follow that the higher you increase the temperature, the higher will be the pressure in a particular location.
This, however, is not always the case. More often as the temperature increases, the atmospheric pressure actually decreases. Why do you think this would be the case? The answer is due to the fact that as the temperature rises, the atmosphere expands, becoming less dense. Even though it is true that individual molecules are each exerting more pressure, the decrease in density is enough to create a lower pressure.