Dashu is de twaalfde zonnetermijn van de vierentwintig zonnetermijnen en tevens de laatste zonnetermijn van de zomer. Douzhiwei, met een zonnelengte van 120 °, wordt gevierd van 22 tot 24 juli in de Gregoriaanse kalender. ‘Shu’ betekent heet, en 'Da Shu’ verwijst naar de extreme hitte van ontsteking. De Grote Hitte is relatief heter dan de Kleine Hitte, en het is de zonneterm met de sterkste en heetste zonneschijn van het jaar, met het hoogtepunt van “heet en vochtig stomen” op dit moment. De klimaatkenmerken van Dashu omvatten hoge temperaturen, intense hitte, frequente onweersbuien, and typhoons.
The Dashu solar term falls around the middle of the “Sanfu” period, which is the hottest time of the year. During the Great Heat season, the sunshine is intense, the temperature is high, humid, and rainy. Although there may be unbearable heat and humidity, it is very beneficial for the growth of crops, and crops grow the fastest during this period.
Since ancient times, there has been a custom among the people to drink herbal tea (Fucha) during the three days of the Great Heat; Fucha, as the name suggests, is a type of tea consumed during the Sanfu period. This tea, brewed with traditional Chinese herbs, has a cooling and heat relieving effect. Daarnaast, there are customs such as burning incense and sun drying ginger. Dashu “is the hottest and most humid season of the year, during which the focus of health and wellness is on” preventing heatstroke “en” dispelling dampness “.