The Summer of 2018 officially started at 6:01am ET on June 21.
The Summer Solstice occurs when a planet’s rotational axis, or geographic pole on either its northern or its southern hemisphere, is most inclined toward the star that it orbits. Here on Earth, the maximum axial tilt toward the Sun is 23.44°; on the summer solstice, the sun and is directly above the Tropic of Cancer.
Climatologists and meteorologists consider the start of “Meteorological Summer” to be June 1. And while it’s the season known for warm temperatures and tropical cyclones around North America, the Earth is actually closest to the Sun in the Winter. On January 4, the Earth will reach perihelion (peri meaning “near” and helion meaning “sun”) and the earth is 3.1 million miles closer to the sun than at aphelion (on July 3 when the earth is furthest from the sun). Earth’s distance from the sun is not what causes the seasons (it is the The Equinox and Solstice) but it does affect the length of them. Around perihelion the earth is moving around 2,240 miles per hour faster than at aphelion which results in winter being 5 days shorter than summer. The word “winter” comes from the Germanic wintar which in turn is derived from the root wed meaning ‘wet’ or water’, and so signifying a wet season. In Anglo-Saxon cultures, years were counted by the winters, so a person could be said to be “2 winters old”.
The summer solstice on June 21, also known as the longest day of the year, provides roughly 16 hours and 38 minutes of daylight.