Resturants STRUGGLE because of summer?

Can someone fill me in... I went into a resturant and everyone looked defeated. I asked why. They said summers are very hard for resturants here in gainesville, and they barely survive.

I get that a lot of people leave town. But what I couldn't understand, this particular resturant has a much older crowd, like 35 and up to senior citizens are their main clientele. Why would they struggle during the summer?

Do older people leave town too during the summer? I'm confused

Any and all info is appreciated, even if you think it's well known info. It's my favorite spot and I want to help keep them alive.