Meteorologists say fall starts on Sept. 1. Most people say the fall begins on the fall equinox, three weeks later. Both are right, and the difference comes down to how you measure a season. Meteorological fall is easier for climatological averages, while the fall equinox is the moment of roughly 12 hours of day and night for all. The key is that fall is here, and it is time to break out the pumpkin spice.