Do you watch the weather radar?
Which direction does most of it come from...that would be your prevailing wind direction.
Here it mostly comes from the west.
Was the coop door closed?
That can make a difference, both in allowing air to flow in the doorway and as an 'exit' for air coming in the upper vents.
You felt it on your knees/arms...but where exactly was the breeze coming from?
Do your prevailing winds come right at the large front overhang?
It's hard to say how much 'breeze' you're feeling, and if it will reach the roost.
Hanging some flagging tape around, up high(front and back) and near roost, can help assess the air movement.
One thing you can do, is to staple up cardboard to the bottom of the rafters over the roost. They...
Be careful it doesn't stick and pull the BJ up. Dowel rod is a better idea. Ventilation is probably the most important at this point.
I call them the 'Weather Guessers' and know they cannot control Mother Nature.
I use weather dot com and weather underground and draw my own conclusions,
which is...
He did fine.
Shouldn't be a problem during the summer....you can lift sides for some ventilation during painting and fair weather....then batten it back down if windy wet weather is imminent.
Good move!
You can still open it partially to work in there, then close it up when needed.
I had a 20 x 20' tarp strung up over my hot tub for months one summer while I fixed it.