By choice I never wish to have the weather showing on my home screen. I can look out of the window......
Anyway, I have had on-off problems with this issue, using Pixel Launcher, which I'm happy with apart from this problem. I have a Pixel XL, fully updated to Pie with the latest patch from this month. The latest "symptom" I have is that when I'm using Wi-Fi, the date AND temperature show. When I switch to cell data, after a few minutes the temperature disappears. On switching back to Wi-Fi, the temperature re-appears again! This only happened towards the back end of 2018 following an update to one of the Google apps but I cannot isolate which one.
I have pretty much everything turned off that I don't use/need, including Google Assistant, location services, Discover. You name it, I've disabled it. And yet I STILL get the damn temperature when using Wi-FI.
I wish Google would just amend the Pixel launcher and give everyone the option of what we can display on our Home screens. Surely it's not that difficult?
It looks like I will have to go to an alternative launcher, which is no great hassle but I like to keep my phone as "vanilla" as possible.