What do you mean by Xia Han?

Late spring cold refers to the weather phenomenon that the temperature rises rapidly in early spring (usually from the end of February to the beginning of March), but the temperature is lower in late spring (usually in April) than normal.

Cold in late spring must meet two conditions:

The first is that the temperature is much lower than the previous stage, and the second is that the average temperature is lower than 10 degrees Celsius for five consecutive days.

In the four seasons of the year, the season with the greatest changes in meteorological elements such as temperature, airflow and air pressure is spring. It is often sunny during the day, which makes people feel "warm wind makes tourists drunk", but it is chilly in the morning and evening, which makes people feel "chilly in spring". This unpredictable "fickle" weather is commonly known as "cold spring".

When the "late spring cold" occurs, winter wheat in the stage of turning green or jointing growth can suffer different degrees of freezing injury, cotton, rice and other crops that have been sown but have not yet been unearthed can rot, and a large number of unearthed seedlings will freeze to death.