In 2011 the heat in SE Oklahoma was seriously oppressive, we had 100 degree days for a longer period of time than I can remember in my 40 years of poultry keeping, the 100 degree days began in May and ended in September with many days in the 110's+. I raise large cochins in several varieties and can tell you that they will not survive this type of heat without shade, misting and fans. I lost over 70 birds that summer and I had fans, water, shade, etc... it was just too hot to survive. Be prepared for hot weather ahead of time and have misters attached to your fans so the evaporative cooling with keep your birds in good shape through the 100 degree weather. Here in the south the misters don't work as well due to the 1000% humidity associated with the heat from hades!
Blessings,
Bo