Indeed meteofrance appears to be monolingual. I would say they're a bit unusual in that though. Most other national meteorological services I know of have forecasts available in at least two languages.

E.g.:

Finnish/Swedish/English: https://www.ilmatieteenlaitos.fi/, https://sv.ilmatieteenlaitos.fi/, https://en.ilmatieteenlaitos.fi/

Italian/English: https://www.agenziaitaliameteo.it/, https://www.agenziaitaliameteo.it/en/

A dozen or so languages (full forecasts available in about half): https://www.jma.go.jp/jma/kokusai/multi.html