My chickens don't know to come in from the weather

[Shadrach]

I think, although I have nothing more than what I've observed to go on, getting out of the rain is learned, usually from mum as @Granitestater implies. I think you will have to teach them.
Getting soaked normally isn't a problem for a chicken in their natural habitat because jungles are warm. It's wet and cold that causes problems. While the chicks are growing proper feathers the mums here will shelter them when it rains. As they get older mum leads them to shelter. So, I think it may be learned behaviour rather than instinctive to take shelter.

 

[TLCMidMichigan]

I wonder if you had one of the night lights that is real "soft"?
It wouldn't give off much light. Providing you have power out there.

 

[Raylo]

Thank you all for your input. Tonight they all went in on their own. I put a brighter light, added the concrete block, and today I added cleats that they were practicing on this afternoon. Yesterday they got quite cold and were happy when I put them inside even though I had to chase them down. I think they remembered how cold they were.... and it is raining again. YAY!

 

[aart]

Tonight they all went in on their own.

Always a relief when they all go in on their own!