This causing Snow Like Field!! bizarre natural phenomenon called ‘Angel Hair’ NSW man posted on Facebook that spiders were raining on his house It is a migration tactic that spiders have used to move across the world The spiders release a streamer of silk that carries them aloft in the breeze The phenomenon usually takes place during particular weather conditions. Everybody knows the phrase ‘it’s raining cats and dogs,’ but how many times have you heard that it’s raining spiders?