Why is it so sultry in summer?

When it rains, due to the prevailing updraft, low pressure forms on the ground. On sunny days, the atmosphere mainly flows downward, forming high pressure near the ground. In winter, the atmosphere sinks due to cold, and a high pressure is formed near the ground. Clouds are difficult to cause rainfall, and precipitation is scarce. In summer, the airflow is heated, forming a low pressure near the ground.

It is easy to form clouds and cause rain, with abundant precipitation.

However, it should be noted that the above analysis refers to the general situation, if it doesn't rain or sunny on that day, or it doesn't rain or sunny when the air pressure is equivalent, it has no comparative significance. If it is not the air pressure of the day, the air pressure on a sunny day is not necessarily greater than that on a rainy day.