Rain-capes rock for biking in wet weather. They replace jacket, rain pants and gloves, and it goes on and off in a few seconds.
I have worn them for years. I made a couple of them out of Sunbrella fabric, and posted a blog post about it here
I like the sturdy fabric I use; it promotes air flow and doesn’t flap.
When using a cape, you do need fenders, and any lights or accessories that are on the handlebars will be covered up.