Edit: Disabled Energized - rebooted, re-enabled Energized and rebooted again. Temperature is still there in Snapchat for now.
I used AdAway to get a list of domains Snap connects to when bringing up stickers, two of which are: weather.sc-jpl.com & aws.api.snapchat.com, so if weather disappears again I will add *.snapchat.com to whitelist and see if that works.
So, I added the following into my whitelist, and have no weather again:
*snapchat.*
.*sc-jpl.*
.*googleapis.*
So back to the drawing board until I find it.