i found this old latin rain spell a few years back in amongst my great grannys stuff. it works for me so give it a try- elementum recolligo huic locus. Commodo mihi vestri vox. elementum unda ego dico vos. permissum pluit. is est meus nos sic vadum is exsisto. roughly translated it means- elements gather in this place. lend me your power. element water, i call you. let it rain. so mote it be. let me know what you think and if it works for you.