Today is the last full day of the spring season. Tonight, at 12:04 a.m. the Sun will be directly over the Tropic of Cancer, signaling the start of the summer season. Today will be the longest day of the year for the Northern Hemisphere with nearly 15 hours of daylight. However, it will be the shortest day of the year for the Southern Hemisphere as they begin their winter.
From this point on, the days will start to get shorter. The Sun will slowly come up later and later and the Sun will start to set earlier and earlier. Eventually, the Sun will be directly over the Equator on September 22nd at 3:44 p.m. signaling the start of the fall season!
As a side note – the reason we have seasons is because the Earth is tilted on its axis. We are NOT closer to the sun in the summer and farther away in the winter!