The sun creates a wave of pressure that hits low points twice a day, one of which occurs a couple hours before sunrise, and this reduction in pressure often results in lower air temperature. This wave is called the solar semidiurnal tide.
The other point of minimum pressure occurs a few hours before sunset. The sun provides heat to the upper portions of the atmosphere, and Earth's rotation causes the redistribution of air. This process pushes air in front of the sun as it rises, leading to valleys and peaks of pressure throughout the 24-hour cycle. While these changes in air pressure are often too subtle to notice along with other weather changes, when the conditions are right, a drop in air temperature before sunset is noticeable.