Frogs don't come out on rainy days.

what you want to ask is why frogs come out on rainy days? Breathe the air. According to the query, we know that when it rains, the amount of oxygen in the water decreases due to the change of air pressure, and the oxygen in the air increases, so frogs will climb out of their nests to breathe fresh air. Frog is an amphibian belonging to Chordata, Amphibia, Anura and Ranidae. Its adult is tailless and its eggs are laid in water.