Thats cool, I'll be having a closer look. I'm working on an xbar plugin app [1][2] that alerts me when there is a warmer day in the coming week.
I used VisualCrossing [3] which seems quite good, and crucially allows 2 weeks historical data, which I think is quite rare. It looks like you offer 2? Darksky did not offer this feature I don't think.
For my use the accuracy is not critical.
[1] https://github.com/mattarderne/clearmycal
[2] xbarapp.com/