First, pick a location and a date:
Neat! Now, querying Bright Sky to get the weather for this location and date in a machine-readable format is as simple as opening this URL:
Notice how the parameters you entered are used in the
date= parts at the end of the URL!
On the right you'll find an interactive preview of Bright Sky's response
And this is how a simple weather app could visualize it
19.3 °C · 14.3 °C