There are two main types of superstitions tying plants and animals to weather forecasting: Those that imply that the flora and fauna "know" what the coming season (typically winter), will bring, and those that rely on the physics, chemistry and biology of living things responding to changing conditions. The former generally don't hold up -- plants and animals react to their past or present environments, they don't predict the future -- but there's definitely hope for the latter.
For example, some say that a profusion of pine cones in fall means a cold winter to follow. This one's a bust: Actually, pine trees can take three years to fully grow cones, and varying their cone production from year to year helps them throw off predators [source: WBZ]. However, you can use pine cones to predict weather in another way: watching as they open or close.
Pine cones are the procreative parts of pine trees. Male versions produce pollen, and pollenated female forms yield seeds. Under dry conditions, the outer parts of the cones' scales dry more than the inner parts, causing the cone to open. This is good news for the tree, since dry, calm weather provide a better environment for seed dispersal. In wet weather, the scales absorb moisture and swell shut, shielding the seeds until better days roll around [source: Burns].