Daily flights from and to Paris CDG airport with a flight schedule that can sometimes be impractical (see the airport website).
Once at the airport, either take a cab (recommended) or use public transportation (more information here).
Another possibility is to take the plane to Paris CDG or Lyon and then either take a bus from Lyon (2h 30min journey) or take the train from either city to reach Clermont-Ferrand.
Clermont-Ferrand is reachable from either Paris or Lyon, see here for more information.
When arriving by train in Clermont-Ferrand, please keep in mind that the unique tram line of the city does not serve the main train station (the stop "La Pardieu-Gare" is not the main train station!). Instead, use bus lines to reach the tram (see here).
Multiple international bus lines stop in Clermont-Ferrand at the bus station "Les Salins", which is located next to a tram stop.
Note that the bus station is not located next to the train station, and is closed on Sundays. If you plan to arrive or leave the city on a Sunday, check carefuly the location where your bus stops.
Trains reaching Clermont-Ferrand depart usually from the station "Gare de Bercy" in Paris. The journey lasts around 3h 30min. One can reach the station:
Please note that the trains between Paris and Clermont-Ferrand are trains with mandatory seat reservation (automatically done when booked). This means that you must respect the scheduled departure time and seat displayed on your ticket.
Trains reaching Clermont-Ferrand depart from station "Lyon Part-Dieu". the journey lasts 2h 30min. One can reach the station from airport "Lyon Saint-Exupéry" by using the "Rhônexpress" train shuttle in "Lyon Saint-Exupéry TGV" train station. The journey lasts auroud 30 minutes.
Please note that both "Rhônexpress" and trains connecting Clermont-Frrand and Lyon are regional train that do not require seat reservation. In particular, this means that the tickets can be used on any train during the scheduled day.
Furthermore, the terminus in Lyon is station "Lyon Perrache" and not "Lyon Part-Dieu". Please be careful not to miss your station when heading to Lyon and arriving from Clermont-Ferrand.
Note that there exists similar bus connections for all train connections mentionned above. Companies like Flixbus or Blablabus offer bus tickets connecting Clermont-Ferrand and bus stations in Bercy (Paris), Lyon Perrache and Lyon Saint-Exupéry (Lyon's airport).