Meteo (Aka: Meteor) has been several elementals in the past.
FFII[US]: Light Elemental
FFIII: Earth Elemental
FFIV: Non-Elemental
FFV: Gravity-Based(Not a specific Element.)
FFVI: Non-Elemental(Mob) Assumed to be Non-Elemental(PC)
FFVIII: Non-Elemental
FFIX: Non-Elemental
FFX: Non-Elemental
FFXII: Non-Elemental(or Aether)
By majority it is non-elemental.
It has a chance to be Light or Earth elemental... Really depends on how SE wants it to be calculated in the game when being casted by a blm.