Certain trees only bloom after the last snow, so the first flowers of the horse chestnut tree can indicate that spring has arrived.
Some plants, such as dandelions and clovers, can accurately forecast rain by folding before a storm. The Scarlet Pimpernel is another flower that responds to incoming rain by closing tightly. The same is true of pine cones, which change shapes according to the humidity in the air. Before rain, when the humidity in the air is high, the scales are flexible enough to remain closed; the drier the air, the more they open.
Maple leaves curl upwards when rain is coming, a response to humidity and strong winds, and seaweed becomes dry and crispy during dry weather, but expands when rain is on the way.
A Little Bit of Everything Else
Many inanimate objects can predict rain rather accurately by responding to the increasing humidity in the air. Wood swells when air moisture is high, making doors sticky and furniture (especially chairs) squeak more. Salt may clog the shaker. Sounds travel better and smells are stronger before a storm.
Low pressure fronts and approaching storms in general, have an effect on the human body too. As blood vessels dilate due to the falling pressure, cavities, arthritic joints, and recently broken bones may become particularly painful.