the traditional chinese lunar calendar divides the year into 24 solar terms. summer solstice, (夏至 in chinese), the 10th solar term of the year, begins on june 21st, 2018.
at this time, much of the northern hemisphere receives the most hours of daylight, but it does not bring the hottest temperatures which will come only 20 to 30 days later.
it is a very important custom to eat noodles at the summer solstice in the south of the yangtze river. people in keqiao, shaoxing will hold dragon boat race at the summer solstice.