They are rooted in Traditional European Folk Craft system , though one of the methods incorporates runes.
But before I "come down to business" , why would You even cast/use weather spells ? Is it not selfish and dangerous to change the weather ? Most certainly yes , but also there are situations where these are justified !
Spell to conjure rain
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On a small, round, pale flat stone ( palm/worry stone or smaller, river stones work amazingly ) draw LAGUZ rune in red ink. Place the stone on the ground, and slowly pour water ( preferably from chalice ) through a sieve onto the stone while chanting :
Open skies and rain be free
On this Earth may poured be
Water Nymphs strike the clouds
May rain fall freely on the ground !
It is done. After the rain You may toss the stone into the river .
Rain summoning incense
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This is traditional mixture that works wonders !!!
Equall amounts of :
Fern
Hellebore and
Heather
Burning these water plants will invoke the rains and water to extinguish their beloved plants .
Word of warning Hellebore smoke can be regarded as poisonous to humans so this incense should not be burned inside.
There You go , enjoy Your weather witchery ;)