Kind of strange behavior, doing that was one of the first things I thought of .. I'd almost immediately swapped out launchers, and didn't have the weather widget on the home screen, but tapping on the weather from the lock screen will launch the weather widget once I pass by the lock screen. It was set to Fahrenheit, and I even changed it to Celsius, went to lock and back, then changed it back to Fahrenheit thinking it may re-read the cache or something, but that didn't work, either. So in the settings, I found an option for Google Assistant > weather, which was also set to Fahrenheit. I changed that to Celsius to cycle through what I'd done before, but oddly, now the lock screen says Fahrenheit while the u/m in Google Assistant > weather says Celsius. When I change it back to Fahrenheit, it still says Fahrenheit. Weird crap, but we're good to go, right? Nope, now, even though it uses the defined u/m, it's stuck on 50 degrees. Even if I change back to the Pixel launcher, the widget on the home screen says 50 degrees, but if I tap on it to open it up, it'll give me the correct temp. Quite baffling.