Long story...they normally do have access to shelter.
I've dried them with towels and placed them in garage with heat lamp on - do u think that will help?
That sounds like a good idea if they got trapped without their regular access to shelter and got soaked.
I know I can trust my adults to go in and out at will and am hoping they taught the 8-week-olds to do the same today in repeated downpours, but if something happened so that they got stuck out in the rain without the normal shelter I'd probably take precaution.
I know that silkies' special feathers leave them more vulnerable to weather.