This extension checks the Forecast API for the weather. It will show the conditions right now, along with the brief summary for the next hour and near future. Other lines show weather for today, tomorrow, and the next few days. The workflow will try to show relevant information depending on time-of-day.
To configure the extension, you must register for an API key. This is linked from within the workflow. A link to log in to Forecast for Developers is also included. Once you have an API key, it can be pasted into the workflow by entering 'w k ' and then your API key. You can also clear your key by entering 'w k clear'. The workflow will verify the API key.
Themes can also be set using 'w u'. At the time, only light and dark themes are included.
Units can now be explicitly set as a preference instead of just location based. You can choose default (based on location), US units, metric units, or UK units by using 'w u'.
Download the master and unzip to make your own changes. Or change the extension to '.alfredworkflow' and double-click to open in Alfred 2. The workflow can also be downloaded from my site.