As Bartholomew's Day, so the whole autumn.
If it rains on Bartholomew's Day, it will rain the forty days after.
Thunderstorms after Bartholomew's Day are more violent. (More violent than what, do you ask? More violent than before, perhaps?)Today we celebrate - you guessed it - Saint Bartholomew the Apostle, patron of tanners, butchers, shoemakers, and bookbinders, among other things. He was martyred for his faith by being flayed alive, and is often shown holding a knife and his flayed skin, as in the painting of "The Last Judgment" in the Sistine Chapel (above) [the face on the flayed skin is supposed to be that of Michelangelo].
FRUIT LEATHER would be a good thing to make today. There are several recipes available online - some good, and some which seem to have left out several key steps. Basically, it is ripe fruit mashed or pureed to a pulp, sweetened if necessary, then spooned onto a flat surface - a plate or cookie sheet (lined with wax paper or foil if you want your life to be easier) - then placed in the sun or in a slow oven to thicken and dry. Once that is done, you can sprinkle on powdered sugar, cut the whole mass into strips, roll them up, and store them in something airtight. And eat them.
Today is traditionally the day that, in the year 79, Mount Vesuvius (having given fair warning for the previous couple of weeks) erupted - spectacularly - burying the cities of Pompeii and Herculaneum. You can read Pliny the Younger's eyewitness account of it here.