This app was mentioned in 10 comments, with an average of 3.20 upvotes
This is not exactly what you're asking for but I'll share it anyway. This app lets you add a quick settings tile for the weather.
https://play.google.com/store/apps/details?id=com.florianisme.weatherquicktile
I don't have 7.0 but I have this app in my wishlist: Weather Quick Tile
It adds weather as quick tile, seems kinda cool
I'm past the era of searching for the best weather app and for the last months I'm ok with just having the weather quick settings tile or checking the weather in the Google app.
It is just a quick glance tile with predictions for the 3 days ahead.
Basically if your phone supports fingerprint gesture to show the quick settings panel and Nougat, it is by far the lightest/ fastest and no nonsense offering for at a glance weather info.
I've been using weather tile in the settings bar in leiu of a widget.
But yeah, Kustom or Zooper Widget maker should be able to do this in about 15 minute of tutorial and 5 minutes of work.
If you are on Nougat, you can check Weather Quick Settings Tile.
Since you have Nougat, maybe you'd like to see weather in quick settings?
Weather Quick Settings Tile
https://play.google.com/store/apps/details?id=com.florianisme.weatherquicktile
If someone wants a simple weather only tile.
I don't know if this solves your issue, but I'm using Weather Quick Settings Tile https://play.google.com/store/apps/details?id=com.florianisme.weatherquicktile