三伏

the second of the three annual periods of hot weather (三伏), which begins in late July and lasts either 10 or 20 days, depending on the Chinese calendar in that year

the first of the three annual periods of hot weather (三伏), which typically begins in mid-July and lasts 10 days

the third of the three annual periods of hot weather (三伏), which typically runs over the middle ten days of August

to mark the start of the hottest period of the year, known as 三伏天

to come to the end of the hottest period of the year (known as 三伏)