In sagolii there's just rain, I've never encountered thunderstorms or showers (pretty sure it was always rain, never showers). I can confirm however, thunderstorms on the third circuit (tranquil paths) and shower in 2nd circuit (costa del sol). I don't know know how bad fair chocobos are affected by those 2 weathers though, as I rarely race in the 2nd and 3rd circuit, though it would be pretty reasonable to think that they both destroy fair chocobos as bad as rain.
