Source: TW
Blust had published a detailed study of this. He note the connection between sunshowers and the fox/jackal wedding in Japan, Korea (not chIna), India, Iran, W.Eur, Basque areas, Finland, Bulgaria, Turkey (wolf wedding). For such an odd connection to be found across different Eurasiatic locales spanning different language families does suggest an early origin in pre-IE inner Eurasia followed by dissemination by the diverging groups. It does seem to be a motif descending from an early Eurasiatic folkloric tradition that might be older than 6000 years.
Notably, in Africa many Bantu and Nilo-Saharan speakers have a motif connecting the sunshowers to an animal birth, like lion, leopard, hyena, fox or elephant depending on the area. However, the Berbers and Algerians (with primarily Eurasiatic ancestry) have the jackal wedding motif instead. It is conceivable that the old African motif was the original one which mutated from a birth to a marriage in Eurasia. If the two have an evolutionary connection this might be a very old motif, especially given some claims of the animal birth motif occurring among Austronesians.
Earlier works note the wedding motif both in northern India and Srilanka but I’ve to date not found it in any Dravidian tradition. If that holds, its entry into India would be from an IE folklore.
One may also note that the origin myth of the Mongols features the famous marriage of the Blue wolf and the fallow doe. It is possible that this is one instance of the folkloric motif being incorporated into a mythology: their aquatic connection is hinted by their swimming across the inland sea to reach their campsite at source of the Onon