h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

According to sea and weather lore, seaweed may be used as a weather predictor because of its tendency to absorb atmospheric moisture. Hang a piece of seaweed outside in a sheltered area (to avoid the rain!). If the seaweed is moist and/or pliable, the air is probably humid, or a storm is approaching. The seaweed is simply grabbing the moisture from the air. If the seaweed is dry and brittle, the air is probably dry and has leeched away any moisture. So does it work? Couldn't tell ya...I live in Los Angeles, and as everyone knows, "it never rains in southern California!" =)

My experience of seaweed as a weather predictor came from my grandfather who was a treasure house of esoteric trivia. The required seaweed is bladderwrack. This is the seaweed that generally litters British beaches and has the lovely little blister-like bits. I know this isn't particularly eloquent but you get the general picture. Anyway, here's how you beat your local weatherman. Hang said seaweed on a nail outside. If, after a period of hanging there mindlessly, you are able to pop one of the "blisters" then the weather should be dry. If, on the other hand, you cannot make it pop - it is probably going to rain.