People in the Southeastern United States feel chilly every spring or fall. That is why?
The mid-latitude north of the hemisphere, because the higher the latitude, the smaller the solar projection angle, so in a unit of time, per unit area, the less solar heat is absorbed. So the colder the air goes north. This phenomenon in autumn and winter is very clear, and the difference between summer and winter is not very large.
Again, from the United States’ geographical circumstances, the central United States has many deserts, away from the sea, it is dry. Therefore, the air in the Northwest compared to the South is usually both dry and cold.
Due to the above reasons, in the spring and fall, the air in the northwestern United States strongly flows down the Southeast, so the warm and humid air in the Southeast is replaced by dry and cold air, so the East South feels very cold northwest wind. Moreover, every time the northwest wind comes, it is often accompanied by rain and clouds. The sky was suddenly full of dark clouds, sunlight was obscured, the relative humidity increased, so it was unusually gloomy and cold. When the cold peak passes, the dry air makes the groundwater rise quickly, so the lower the temperature, which increases the cold feeling. Year after year, making people in the Southeast become a habit of feeling the cold northwest wind.
Not all northwest winds are cold. The wind direction is determined by the local distribution of air pressure in each region. The northwest wind in a small range does not necessarily come from the Northwest. Still, only during the autumn to early spring period, the distribution of barometric pressure across the country is generally Northwest higher than east. South, that is the main cause of the Northwest winds. From late spring to early autumn, the law of barometric pressure distribution in the United States mainland is relatively complicated. The northwest wind is very rare, even though it is not necessarily from the Northwest, but winds from the west. In the north, the Northwest desert was not cold at that time, so the temperature was not so low. So we should not watch the northwest wind is always cold. It is only in a certain area and certain seasons.