So how long have you had them ?? and is this their first time outdoors full time ?? at 12 weeks they should have been outside and used to the temps for quite a long time now. Is the coop one of those little small closed in types toy deals with an attached little run and is that why the temp was 95 ??. When they are exposed to their permanant housing at normal ages of 3-5 weeks or sooner in the summer they will learn faster and become aclimated quicker and get smarter. Now if you have raised them in an indoor sheltered enviroment all this time and are just now putting them outside, they will be seriously confused and it may take awhile for them to figure stuff out and to learn to shelter themselfs, especialy if they have been pampered for 12 weeks indoors they are at a serious disadvantage now especialy as fall and winter nears.
We've had them since they were chicks a few days old. They went outside once they were around three weeks old and we were keeping them in a wire cage until I was able to build their new coop. Temps got to 95 because we got up to the high 80's/low 90's yesterday in ambient temperature. I'll include a picture of the coop in its current state for you. I think they were used to their wire cage, they would put themselves right in there on their own at night if I still had them out in the yard when it got dark. My guess is that if their house gets too hot today they'll bee line out into the run but I told my wife I would ask the chicken gurus anyways. I'll be getting home a from work a little after noon time so I should be able to chase any of them out into the run before the temps climb too much today.