Small Heat is the eleventh of the twenty-four solar terms of the lunar calendar, and the fifth solar term of summer, indicating the official start of the summer season. Great Heat is the last solar term of summer, which falls between July 22nd and 23rd in the Gregorian calendar every year.
On July 7 or 8 every year, when the sun reaches 15° of ecliptic longitude, it is called Slight Heat.
Great Heat is also a season that reflects the heat of summer, and Great Heat means that the weather is extremely hot.