Why did the temperature rise before the cold air arrived?

Generally, before the arrival of cold air, the temperature rises to varying degrees, which is called "front warming" in meteorology. It means that the front of the cold front is mostly southerly, and the back is mostly northwest wind. When the cold front crosses the border, it is still at the front of the cold front, which is controlled by the warm and humid airflow before the front, so the temperature will rise briefly.

In addition, southerly winds usually blow before the arrival of cold air, which will also aggravate the warming of the atmosphere. Therefore, before the arrival of cold air, the temperature in a certain area will rise briefly (about one day). The temperature will drop during and after the cold front crossing.

Extended data:

The temperature behind the cold front is lower. When the cold and warm air masses meet, the density of the cold air mass is high and the density of the warm air mass is low, which makes the cold air mass wedge under the warm air mass and causes the warm air mass to be forced to rise.

In the process of the warm air mass pushing the cold air mass, due to the heavy cold air mass, the warm air mass slowly slides upward along the front, and cools and condenses into clouds, rain and other weather during the slow climb.