The photo above is one of our dear light brahmas, panting during the current heat wave. Here in the Pacific Northwest, we are on severe weather alert, with daytime temperatures expected to reach 103F, and little night time cooling. Last night it was still 90F at 10pm, and 80F at midnight.
Many of the breeds we chose for our flock were selected in part because of their ability to produce eggs reliably during the colder winter months. Since high heat usually comprises only a small portion of our annual weather here in the Pacific Northwest, the task during a heat alert becomes providing as much comfort as we can for all our hens, but particularly those with extra plummage.
One of the first things we did was purchase additional large water dishes. I like to use ceramic crock pot dishes because they are the right height, and with their thick dish walls they keep the water temperature cooler longer. The additional dishes, as well as the food have been moved to a part of the chicken run that gets full day shade. What this will mean for the hens during the hottest part of the day is that they will be travelling into the coolest part of the yard to get water and food, instead of into what will turn into the hottest part of the yard.
Even so, in the shade the ambient temperature is at least 90F during the hottest part of the day!
At this point I have opened every venting hole in the coop that I can. During the day I also open the main coop door, and put an old screen door in front of it to allow maximum air flow in the coop. The chickens still want to lay their eggs inside the coop--some are smart enough to choose the coolest part of the coop, and others keep travelling to the west-facing part of the coop where the nesting boxes are.
Either way, we are doing everything we can to adapt our routine to try to keep the hens comfortable.