archaeometerology - I just made that up

If you need rain here's who you have got to call
Ningirsu is the god of rain, fertility and irrigation in Sumer and Babylon. He is depicted as an eagle with a lion's head.
Baal, "the rider on the clouds," is the god of rain, thunder, and lightening.
As Indra is the god of rain, people sing songs to Indra and pray for rain.
Bushman is the god of rain wind and breath.
Mensäbäk is the god of rain; his name means "Maker of Power." Most interesting of all, Hesuklistos is Jesus Christ, the god to foreigners, who the Lacandones believe to be the son of Äkyantho', who is the god of foreign people and objects.
Tishtar is the god of rain originating from Varukasha Sea (Farakhkart) and distributing water among all countries
Rudra is the god of rain and thunder
Ilojin is the god of rain, of which the tropical Fenstre receives copious amounts. It is Ilojin who brings the monsoonal deluges for half of the Fels year.
Chac is the god of rain, and he is unhappy at the move at the WTO to privatise water, which Chac gave to everyone
Tlaloc is the god of rain, Leonardo is the god of... of... well, you decide.
It seems natural that the masks used by local farmers for rain supplication would be Ryujin, as this is the god of rain
Phya Than is the God of Rain who must be presented with shooting rockets come the sixth month of the lunar calendar
The Rato Machhendranath (rato=red) is the God of rain as well as the God of mercy.
Sabi is the god of rain.
Among the Dinka Deng is the god of rain
Dai Wong is the God of Rain and the guardian of the farmers.
The Thunderbird is the god of rain in our land. His wings are the thunder, his eye is the lightening, he spills the water from his back.

Tetnut- is the goddess of rain, moisture, and dew. She is said to share one soul with Shu.
Bunzi is the goddess of rain and fertility