Autumn is the season after summer and before winter. In the Northern Hemisphere, autumn weather extends from late September through November. In the Southern Hemisphere, autumn weather begins in March and continues through May. People living in the tropics rarely consider autumn a distinct season because the temperatures there change little from month to month. Many Atlantic Ocean hurricanes occur during autumn.
During autumn, many kinds of trees shed their leaves, which then fall to the ground. For this reason, many people call autumn fall. Autumn also serves as harvesttime for many crops. Many autumn holidays and festivals began as harvest celebrations.
In the middle latitudes, early autumn days generally feel warm, and nights are cool. As autumn progresses, the air becomes chillier, and the number of daylight hours decreases, particularly in the polar regions. Birds migrate toward the equator. Frost often forms at night, and the first light snows fall.
