What changes from tomorrow after September equinox?

The September equinox occurs when the Sun crosses Earth's equatorial plane, as Earth's 23.5-degree axial tilt means neither hemisphere is tilted more toward the Sun. Both receive nearly equal sunlight. After the equinox, the Northern Hemisphere receives progressively less direct sunlight, causing days to gradually shorten and nights to lengthen as it moves towards the December winter solstice.