Why does the 'faucet' turn on almost every year by mid October?
Sunlight is now most direct south of the equator; the tilt of the earth's axis is increasingly pointing away from the sun, and that results in an increasing contrast in temperatures from north to south. That sharper contrast in temperatures strengthens the jet stream, leading to stronger storms. While the temperatures in the tropics aren't cooling significantly, the temperatures in the Arctic are plunging rapidly. That colder, more dense air is pushing the jet stream farther south into the Pacific Northwest....leading to wetter weather.