I don't think its directly related to the rain. My guess would be they are the condensation drains from the pan under an AC unit that is installed in the attic.

In most areas the primary drain will be into a rain gutter or a plumbing drain where you don't see the water, and the exposed pipes you see in your picture are the secondary drain. Seeing water coming out of the secondary drain alerts you that the primary drain is plugged with debris.

Bruce

Bruce is correct. Secondary drain for AC. You do need to get primary drain unclogged. Making sure the line is clear is routine house maintenance.