> Many earthworm and soil experts have settled on a version of this explanation: Moving around the soil is relatively slow and difficult, even for earthworms. They can cover a lot more ground on the surface...when it rains, the surface is moist enough for worms to survive and remain hydrated. For a few species, they can more easily move about and find mates. For other earthworms, it may well just be a way to disperse and move into new territory.

Makes sense to me especially with other notes about the absence of young worms. And it feels like predators might be at least a little less active during the rain.

Anyway as a sucker who always helps a worm on the sidewalk out this article was super helpful :)