I don't like cutting grass in general, but I especially dislike it when it rains! But a robot doesn't really care. A lot of the robot lawn mowers on the market now are perfectly able to cut damp grass and don't really mind getting wet, as far as they don't get stuck in the mud! But there are some caveats - depending on the model, the robot's likelihood of getting stuck or obstructed will either increase or skyrocket when the conditions get worse. And the end result might not be as clean as it would be otherwise.