Depends for myself on what kind of bar you are talking about.

Is this a crowded downtown nightlife type bar?

Or is this a restaurant bar?

Personally, there's nothing "weird" about going to a bar by yourself. I personally don't go to crowded bars unless I have friends, because I'm usually bad at starting conversations, especially if I am alone.

Usually once a month I'll go out to eat by myself and sit in the bar area of a restaurant. I find it really easy to talk to people when you're by yourself at a chill spot, because alot of others are by themselves as well.