This would be a very harmless garden orb weaver. Sorry I can't get your little friend to genus or species from your photo.
These do like porches especially near lights and windows, that is where the bugs are.
They are very beneficial, no need to kill them. If your little gal is out of the way, you might just let her stay the rest of the season.
This is similar to what you are dealing with:
Vietnamese Jumping Spider.
They can leap up to 4 feet and are deadly poisonous.
What kind of spider is this? It's huge and made a huge web on my porch!
