Rainfall in the Bay Area often brings relief from dry conditions, but it also triggers a noticeable increase in pest activity. Homeowners and business owners frequently report ants, spiders, rodents, and other pests appearing seemingly overnight after a storm. This surge is not random. Rain fundamentally changes pest environments, forcing insects and animals to adapt quickly, and homes often become the most attractive refuge available. Understanding why pests spike after rain can help Bay Area residents recognize early warning signs and take action before a minor issue becomes a full infestation.