Is "heavy snow" the coldest solar term in a year?

No. Great cold is the coldest time of the year.

"Great Cold" is the last of the 24 solar terms. At this time, the cold wave frequently goes south, and most parts of China are in a cold period. In the severe cold season, the average temperature in most parts of southern China is 6℃ to 8℃, which is nearly 65438 0℃ higher than slight cold. The proverb "slight cold and cold, cold into a ball" shows that the great cold solar terms are also the cold period of the year.