暑中見舞い（shochu mimai）： Summer greeting

It has been very hot and humid these days. In Japan people tend to send greeting cards twice a year. One is a new year's card called nengajyo (年賀状), and the other is a summer greeting card called shochu mimai (暑中見舞い).
The set phrase of the new year's card is shinnen akemashite omedeto gozaimasu(新年明けましておめでとうございます), A Happy New Year. And the fixed expression of the summer greeting card is shochu omimai moushi agemasu (暑中お見舞い申し上げます).
The special issued postcard for summer greeting is called kamomeru (かもめ～る). It has numbers at the bottom of the front, and they have a drawing in September. Shochu mimai is sent during doyo (土用), 18 days before the first day of autumn, risshu (立秋). After risshu, people send zansho mimai (残暑見舞い) instead of shochu mimai.　Zansho (残暑) means the late summer heat. The stereotype of zansho mimai is zansho omimai moushi agemasu(残暑お見舞い申し上げます).