What does it mean that autumn tigers are raging?

This means that after beginning of autumn, the weather is still hot and unbearable.

According to Baidu Encyclopedia, this is a folk saying that after beginning of autumn, the weather is still hot and unbearable. Traditional Chinese medicine believes that the autumn tiger is called "autumn tiger" because after the summer heat, the climate is in a transitional stage of "Yang disappears and Yin grows", and the autumn sun is like fire and the temperature is high.

Beginning of autumn is the 13 of the 24 solar terms, and the first solar term in autumn falls on August 7th or 8th every year. In China, beginning of autumn is the beginning of autumn.