The day of Daeseo, what is traditionally the hottest day of summer — literally the “Big Heat of Summer” (대서, 大暑) — falls on Tuesday, July 23, this year. It marks the beginning of the 12th of 24 solar terms throughout the year. Daeseo is always in the sixth lunar month and usually falls around the end of July.
Daeseo follows after Soseo (소서, 小暑), which was literally the “Day of Minor or Lesser Heat” on July 7 earlier this year, and precedes Ipchu, or the “Beginning of Fall” (입추, 立秋), which will be on Aug. 8 this year.
The solar term that begins with Daeseo marks the hottest period of the year and follows the end of the rainy season, prompting the old saying that, “Even goat horns melt on Daeseo.”
Three of the Year’s 24 Solar Terms
Soseo (소서, 小暑), the “Day of Minor or Lesser Heat”, July 7
Daeseo (대서, 大暑), the “Big Heat of Summer”, July 23
Ipchun (입추, 立秋), the traditional beginning of fall, Aug. 8
The Hottest Days of the Year
Chobok (초복, 初伏), a 10-day period, starting July 12, 2019
Jungbok (중복, 中伏), a 20-day period, starting July 22, 2019
Malbok (말복, 末伏), a 10-day period, starting Aug. 11, 2019
The day sometimes overlaps with Jungbok (중복, 中伏), the second of the three hottest days of the year, but not this year. On both Daeseo (July 23, 2019) and Jungbok (July 22, 2019), people prepare special foods and drinks, and escape from the heat to nearby mountain valleys and streams. Or they just head down to the Hangang River. Or stay at home, close the blinds and turn up the air conditioning.
When the monsoon season continues late, Daeseo can bring heavy rainfall.
Around Daeseo, farmers weed and prepare compost. Juicy summer fruits, such as watermelons, melons and vegetables that ripen in this period, are considered to taste better than at any other time of the year. Wheat and barley are also ready to be harvested early around Daeseo.
As for Seoul, the Korea Meteorological Administration (KMA) is predicting temperatures of 23.9 C to 24.7 C, with 259.3 mm to 423.7 mm of rain (75 F to 76.5 F, with 10.2 inches to 16.7 inches of rain) for the week of July 22 to July 28. Be sure to get some watermelons, head to the mountains or riversides, and keep cool this Daeseo.
This article was gleefully pilfered from the National Folk Museum of Korea site and its Encyclopedia of Korean Folk Culture.
By Gregory C. Eaves
Originally written in 2016. Updated for 2019