Fall begins on September 23rd in the Northern Hemisphere, or would that be Autumn? They are both
interchangeably known as fall in the US and Canada, this is one of the four temperate seasons.
Autumn marks the transition from summer into winter, in September or in March for the Southern Hemisphere when the arrival of night becomes noticeably earlier and the temperature cools considerably. One of its main features is the shedding of leaves from deciduous trees as they pave way for further growth.
Some cultures regard the autumnal equinox as mid-autumn, others with a longer temperature lag treat it as the start of autumn.
Meteorologists and most of the temperate countries in the southern hemisphere use a definition based on months, with autumn being September, October and November in the northern hemisphere, and March, April and May in the southern hemisphere.