Checkmark,

As long as you have some good airflow they will survive. Understanding how heat waves go, I been there, done that..LOL

You may get a hermi or two out of it, but some is better than none if it's all you have. Being that Seattle doesn't normally see this kind of heat is one reason why you can get away with an attic grow. Down here our attics will top 120 F during the summer with no problem. That'll scorch a plant. Done that too. LOL