There is an old weather rhyme which opens with allegedly infallible signs of rain:
The hollow winds begin to blow,
The clouds look blank, the glass is low,
The soot falls down, the spaniels sleep
And spiders from their cobwebs creep.
Now the spider owes its reputation as a weather forecaster to a French man by the name of Denis Quatremere-Disjonval, who wrote a book upon the subject in 1797. Spiders, it seems, are indolent when rain is due; they fall from the walls and forsake their cobwebs in the garden.
Moreover, when it is about to rain, spiders are said to fix the frame-lines of their webs unusually short. If, on the other hand they make them long, the weather will be fine for weeks to come. It is also a fact well known to spiders that flies fly low in a moisture-laden atmosphere, so we may expect the rain when spiders spin their webs close to the ground.
Unfortunately, another French man had a very different theory about spiders and the weather. The eminent and much-respected 19th-century entomologist, Jean Henri Fabre, also studied spiders and came to the conclusion that they have no predictive powers at all. According to him they do pretty much the same kind of things at more or less the same time every day, regardless of the weather.
Be this as it may, there is an interesting conjecture about the origins of perhaps the most enduring piece of weather lore concerning webs and spiders: that when gossamer, or a silken entanglement of spiders' webs, is found in the rigging of a sailing ship the weather will continue fair.
Many species of spider, it seems, disperse their populations by allowing themselves to be wafted over long distances by air. On sunny breezy days, a spider with a wanderlust will climb to the top of some convenient projection in its native patch and weave a silken thread that may be several yards in length. While this gossamer, as it is often called, is waving in the wind, the spider releases its hold, climbs out along the thread, and both it and the gossamer are carried off.
Now the story goes that this aeronautical activity is often stimulated by a spell of fine, sunny weather in late autumn. And in days gone by it was associated with "St Martin's Summer", an unseasonally benign interlude that sometimes occurs around the saint's feast day in mid-November. Moreover, it was the custom to eat a goose on Martin's Day, so this spiderly activity became associated with the "goose-summer", and hence the name "gossamer".