To protect your birds in this hot weather here are some tips from my experience of poultry keeping (40+ years!)
Ensure birds are able to access a shaded, cooler area.
Avoid feeding corn, as this is is heating, thsi is why grains are usually fed in the afternoon especially in winter, they take longer to digest and keep birds warm at night.
Place galvanized drinkers in the shade to prevent evaporation and birds going thirsty.
Move housing to shaded areas, or provide shade.
Spray chicken house roofs with water to aid cooling.
Let birds out of houses earlier, but remember the fox may still be around.
Let birds free range so they can find their own cool spots.
Put unwanted broody birds in cool place, as they may overheat in nest boxes.
Fill all your drinkers, and spot around so birds can access easily.
Consider an automatic drinker if you are going to be away from your birds.
Avoid moving or stressing your birds whilst it is still hot.
Put sun block on exposed flesh on hens, and large combs, or keep in shade.
Keep a close eye on red mites and lice and treat immediately.
Check night temperature in closed houses, try to improve ventilation, wel dmesh panels can be used to replace doors.
My stag turkey loves being sprayed, most birds hate it, but you could try it.
If a bird has suspected sun stroke, try putting a damp flannel under the wings to aid cooling, and seek veterinary advice. Do not try rapid cooling, as it may die of shock.