What does the rural saying "a spring rain is warm, an autumn rain is cold" mean?

In spring, the warm air in the Pacific Ocean extends to the northwest due to the increasing exposure of the sun in the northern hemisphere. Rain occurs when warm air advances northward and rises at the boundary of cold air in the north. In the process of sliding up, it pushes cold air northward at the same time. As a result, warm air often occupies the ground originally occupied by cold air, so before the arrival of warm air, there is often a spring rain in these places. The feeling of "a spring rain and a warmth" is for this reason. When it rains in a place, it gets warmer under the control of warm air, and then it will rain again if cold air bounces south. When the cold air front passed, this place was controlled by cold air, and there was a cold weather for a day or two temporarily. But in a few days, this cold air will absorb a lot of solar radiation heat and be affected by the warm ground in the south, so that its temperature will rise and it will gradually turn into warm air. Therefore, people always feel that it is always warm after the rain in spring, as long as the weather is fine.

Besides, why is it getting colder every day in autumn? This is mainly because the direct rays of the sun gradually move southward, and the light and heat irradiated in the northern hemisphere decrease day by day, which is also conducive to the enhancement and southward movement of cold air. After several cold air southward, the local temperature became very low. People often say that "an autumn rain and a cold" is the truth.