Outside ceremony next weekend....cover up?

I think it depends on the weather in your area and the time of day. Anything under 60, a wrap might be appropriate.

I wouldn't think it would be necessary for 70+.

If the weather stays like that, and it's only the ceremony that's outdoors, I think they should be fine. They can always bring their own sweater, etc. for later if they get chilly.

I would give them the option of having one. 70's everywhere is different. 70's in Michigan is someplace else 60's. But 70's where you are could be 80's. Weather is a tricky thing. I would have them handy.