Yup, not necessary… while its easier to check code on codepen, its not the only way… and Ill note, the further allong you get in the projects the more advanced the people are who will be able to help you…and they will likely know how to use developer tools to check out and play with your website the same way you can in codepen.
I self host my projects and haven’t asked for a project review since my portfolio project (though I really should…I need to work on asking for feedback) all the same, I get private messages from people who checked out my projects and offered feedback.
So…you do you. Codepen is a great option for people who dont have their own hosting, but if you already have your own, may as well use it. Not to mention it will make deploying your weather app a million times less stressful.
ETA Sorry Sky…meant to hit reply to the OP not to you…eep!