Nice work on your weather app. It is very simple though, you are right. You could try and add the city name as an additional challenge. A background image and a slightly narrower view for mobile wouldn't hurt either.
For your code, you could simplify it a lot by getting rid of that switch statement. The weather icons you've included in your project are designed to work with the Dark Sky Weather API. All you have to do is prepend
wi-forecast-io- to the icon code that comes back from the API.
$("#icon").addClass('wi-forecast-io-' + weather.currently.icon);
For your location question, one common approach to this is to call a function when you get the location - and send the location data as an argument in that function.