The science behind the upcoming summer solstice ☀️

Next week the Northern Hemisphere will endure “the longest day of the year” during the summer solstice

On Wednesday, June 21, the Northern Hemisphere will endure “the longest day of the year” on the summer solstice

On Wednesday, June 21, the Northern Hemisphere will be tilted closer to the sun than at any other point during the year. The maximized tilt means we will see the most amount of sunlight and the least amount of darkness.

San Antonio can expect the summer solstice to take place at 9:57 a.m. CDT, when the Sun reaches its highest point in the sky.

The science behind the solstice

The term solstice comes from the Latin term solstitium or sol, which describes the sun standing still. On the day of the Summer Solstice and a couple of days before and after, the sun can be seen taking a slightly more direct path across the sky.

Normally, the Earth’s 23.5° tilt causes the sun’s path to appear arched. On Wednesday, the sun will travel most directly overhead along the Tropic of Cancer.

Meteorological vs. astronomical seasons

Meteorologically, the summer solstice does not define the start of the summer season. Instead, the four seasons are evenly split over three months for simplicity.

Temperatures also don’t usually hit their peak until a few weeks after the summer solstice. This is because there is a larger imbalance of daytime heating and nighttime cooling between July and August. Incoming radiation from the sun during the day exceeds the radiation leaving our atmosphere at night, essentially meaning that the heat doesn’t fully escape back to space and builds through the summer.

Fun facts about the solstice

  • While the Northern Hemisphere is experiencing the summer solstice, the Southern Hemisphere is celebrating the winter solstice.
  • The Tropic of Cancer is 23.5° north of the Equator, which creates the opportunity to see the sun travel directly across the sky here.
  • Even though the sun reaches the highest point in our sky on the summer solstice, the Earth is at its farthest point from the sun on July 6th at 3:06 PM CDT. This moment is called the Aphelion.
  • Compared to the winter solstice, we will endure an additional 3 hours and 46 minutes of sunlight on the summer solstice.

San Antonio weather before and after the solstice

This past week has felt extremely hot thanks to the excessive humidity! While thermometers have settled into the 90s, feels-like temperatures have been able to climb well into the triple digits at times.

As the summer months continue on, brace for more humid and hot weather. Temperatures normally hit their peak in late July through August.

Be sure to always use sunscreen and stay hydrated!

About the Author:

Leah Mata-Rodriguez is an intern with the KSAT Weather Authority team. She is a rising senior at Texas A&M University majoring in Meteorology. Originally from Pearsall, Leah grew up watching KSAT 12 before and after school. She always looks forward to eating food from Mexican restaurants and bakeries around San Antonio and her hometown.