Why is the air pressure high in sunny days and low in cloudy days, high in winter and low in summer?

Winter is dry and cold, the air density is higher than that in summer, and the water vapor content is lower than that in summer, which makes the oxygen concentration higher than that in summer, so the air pressure in winter is higher than that in summer. The water vapor content in the air on sunny days is much less than that on cloudy days, and the relative oxygen concentration is higher, so the air pressure is higher than that on cloudy days.

We feel chest tightness on cloudy days, because our lungs need to expand so much that the air pressure in the lungs is lower than the outside air pressure to let air into the lungs.