What is Bad Design?
There's plenty of opinion about what is bad design, but instead of boring you with my opinion, let's just take a look at it.

Bad design fails to give the user the information they are attempting to find. This could not be more obvious than the Weather.com homepage. When 20% of the content above the fold is actual weather information, you have a very big problem.

As a user, I'm here to find more information about my local weather. Instead of automatically detecting my location and showing it, I have to search for it. And then when I'm displayed that information, the delivery of it fails a basic UX test: display information the user seeks prominently and overtly.

Pay no mind to the page width inexplicably changing from 1200px to 980px, but now even less of the site is showing me pertinent weather data and along with squatting prego, I get 3 old dudes who found trash washed up on the shore and a girl who sold a diamond. Where am I? — Also, why is there a weather map of Pasadena California below this area I’ve highlighted?
The reason I came here was to find out what kind of weather is happening next week. Of course that requires another navigational click. Trying not to get distracted by prego, Lincoln, and a freaking giraffe I locate the needed information. Awesome. Thunderstorms will delay my flight to New York. That was a painful journey to get that information.
Fixing Bad Design
First of all, select the city I’m in automatically. If I want to see a different city I’ll use the search like I would normally do anyhow. Second, show me some quick data so I can be on my way. Third, remove that distracting background, the ridiculous filler stories and move the advertisement to a location nearer to where a user first looks.

Now on to the detail view. Here there’s more work to be done. Let’s remove the bullshit stories at the top that have ZERO relevance to anything I want to see. Let’s go with a single ad instead of a 3 (above the fold). Offer up the map view from the start, and let’s expand the time frame a couple of days. Not only that, but let’s keep the same width and page elements from before and keep the horizontal navigation trend.

Granted, it’s not the prettiest as I kept the same UI elements, but is this not more pleasing to look at with just a few simple changes? You’re Weather.com you should kill it at showing WEATHER data. Go out and hire a solid UX designer and get your act together.