It's winter. Why is it so hot now?

Since June this year, the western Pacific subtropical high, the Atlantic high and the Iranian high have been strengthened in stages over the northern hemisphere subtropical region, forming a large-scale global warm and high pressure zone. Under the control of warm and high pressure area, descending airflow prevails, which is beneficial to the rise of ground temperature. In addition, under the action of a wide range of high-pressure areas, the air is relatively dry and it is not easy to form clouds, which also makes the solar radiation reach the ground more easily, leading to frequent high temperatures and high intensity, thus causing persistent high-temperature heat wave events in many parts of the northern hemisphere.