Answer:

The time is June 21 or June 22, the summer solstice every year.

Yulin Dog Meat Festival

The Yulin Lychee and Dog Meat Festival is a spontaneous festival formed by the citizens of Yulin, Guangxi, China. It is held on June 21 every year and is a folk custom to celebrate the summer solstice.

There is a folk saying: "Winter fish gives birth to summer dogs." Since dog meat is warm and easy to get angry, the summer solstice is the day when the "yang energy" is strongest. Eating lychees and dog meat is very "heaty" "The thing that coincides with the "yang energy", "using yang to control yang" will not attack the heart as hot as usual, so eat a big meal with ease on this day.

However, the festival has been boycotted by animal rights protection groups and dog lovers because of the slaughter of a large number of dogs.