So I was looking at the weather on my cellphone (a Google phone) and I noticed the default Android weather app had a direct link to the weather.com page with a variation of the URL we are using. Not sure if everyone knows this already, maybe I'm last to the party as usual. It appears you can control the temperature units with a parameter. The phone app uses:
https://weather.com/weather/today/l/<lat>,<long>?temp=f
https://weather.com/weather/today/l/<lat>,<long>?temp=c
With a little experimenting, using the locale ID will control the language, and a "units" parameter is also accepted in lieu of "temp" (but not the hybrid option):
https://weather.com/<locale>/weather/today/l/<lat>,<long>?units=e
https://weather.com/<locale>/weather/today/l/<lat>,<long>?units=m
So using something wacky like...
https://weather.com/ru-RU/weather/today/l/48.8566969,2.3514616?temp=f
...will get you the weather in Paris France with Russian descriptions and Fahrenheit/English units.
So the trick of controlling the units with the locale isn't necessarily the only option.