Telchur is the Oeridian god of the north wind, winter, and cold. Vatun is the Suel god of of cold, winter, arctic beasts, & the northern barbarians (e.g., Frost, Cold, Ice).
Istus is a Baklunish deity concerned with fate, destiny, divination, etc.
FWIW, Sehanine Moonbow's portfolio is "Mysticism, Dreams, Far Journeys, Death, Full Moons, Transcendence", which could be interpreted as at least touching on fates, destinies & the like.
All those deities are described in the Living Greyhawk Gazetteer, IIRC.