From the vice-president of my division:
I was just looking at my calendar for the next couple of weeks, and realized that I'd forgotten to send out important mail on Memorial Day. For the past couple of years, I've asked my team not to schedule meetings on Friday afternoons during the summer (Memorial Day to Labor Day). I'd like to do that again this year.
The reason is simple: it's summer, it's (usually) sunny, and the rest of the year it isn't.
This kind of thing only works if everyone tries pretty hard to stick to it. So please do try to avoid scheduling meetings on Friday afternoons after 1pm, until Labor Day. There are going to be times when it's unavoidable, but with any luck there won't be too many of those.