After the warmest meteorological summer on record, temperatures in Lancaster County have started to tumble.
Temperatures this weekend will generally stay in the mid 60s, but the lows at night will dip to the lower 40s. Chances are, you've also seen coffee shops promoting fall flavors and the appearance of Halloween candy.
But, when does fall actually start?
Tuesday, Sept. 22, is the first official day of fall.
Seasons change primarily due to our Earth's tilt on its axis, which is 23.5 degrees, according to National Geographic.
These events, known as Equinoxes, only occur two times per year: the first day of spring (Vernal), and the first day of fall (Autumnal).
Equinoxes are different than solstices, which mark the start of winter and summer, as solstices mark when the Earth is closest and farthest from the sun.