The answer for a chicken dressed for winter
A Silkie chicken in a heatwave needs shade cloth over her run, a coop that breathes on more than one side, and water she can reach without crossing sun-baked ground. Her silkied feathers lack the hooks that zip a normal feather flat, so each plume stands loose and fluffy, holding a layer of warm air against her black skin. A Silkie cannot fly to a high, breezy perch to escape that heat, so everything she needs — shade, water, dust — has to exist at ground level within a few steps.
Panting, wings, and the broody Silkie problem
A Silkie chicken cools herself by panting and by holding her wings slightly out from her body, so a hen sitting fluffed tight with her beak closed on a mild morning and a hen spread flat, panting, in a nest box at noon are in very different states. Silkies are famously committed broodies, and a broody Silkie will sit in a stifling nest box through a dangerous afternoon rather than abandon eggs or even imaginary eggs. Lift a broody hen off the nest during the hottest hours, set her in shade near water, and block the box until evening if she returns immediately to bake. A Silkie who is limp, pale around the face, or panting with her eyes half closed needs shade and water at once and a call to a poultry-savvy veterinarian if she does not brighten quickly.
Water, dust, and ground-level shade for this breed
Give this Silkie chicken more water points than feels necessary, in shallow dishes she cannot tip her crest into and soak, refreshed whenever the water warms in the sun. Her large, feathered crest can fall over her eyes when wet, so keep drinkers clean and low rather than deep. Provide a dry dust-bathing patch in full shade — loose soil in a tray works — because a Silkie works dust through those loose feathers to stay comfortable and keep mites down, and she will not cross a blazing run to reach a bath placed in the sun. Wetting a shaded patch of earth gives her a cool surface to stand and scratch on through the afternoon peak.
Coop nights matter as much as hot days
A Silkie chicken who survives the afternoon can still be lost to a coop that stored the day's heat, so open every vent the coop has on hot nights, check that roosting space is not crowded plume-to-plume, and feel the air inside at hen height after dark. Her five toes and heavily feathered feet collect mud and droppings in a damp, hot coop, so pick up her feet during the heatwave and clean anything caked there before the skin beneath stays wet and sore. Keep nest boxes and the pop-hole routine calm at dusk, because a flustered Silkie flushed into a dark run at nightfall is a bird who may not find her way back in.
Airflow openings are also escape openings
Every vent and propped coop door that saves a Silkie chicken in a heatwave is also a gap she or a predator can use, so mesh every opening you create and count your hens in at dusk by name rather than by a glance. If this Silkie does slip out and settles under a neighbour's shrubs, KinsLe's Lost Pet Alert System can notify nearby members with her description, letting the person who spots that unmistakable fluffy outline reach you directly.