Welcome to summer! The start of the season is marked by the Summer Solstice, which falls on June 21st this year. https://www.youtube.com/watch?v=G7pAx8iVn-w   The season officially kicks off at 11:54 am EDT. This time marks the moment that the sun is directly over the Tropic of Cancer, or 23.5° latitude North. What is so significant about 23.5 degrees? Well, first we have to back up to the reason we have seasons at all.   The Earth is titled on its axis by 23.5°. The Earth makes a complete revolution around the sun every 365 days, but the tilt's orientation does not change during the year. At different times during the year, the northern or southern hemisphere is closer to the sun. During that time, the hemisphere tipped toward the sun experiences summer. https://gph.is/g/469oe08 The Northern Hemisphere is tilted toward the sun in June. The sun's rays hit the Northern Hemisphere more directly than at any other time of the year. More direct light means more heat, giving us our hot, summer days. Today marks the longest day, and likewise shortest night, of the year. The farther north you are, the more sunlight you'll see during the solstice. If you live near the Arctic Circle, the sun never really sets during the solstice. Across the continental US, most spots will see between 14 and 16 hours of daylight. Friday might be the longest day of the year, but the hottest weather of the year is still to come. This is due to the "lag of the seasons". Before we feel the most sweltering summer heat, we have some warming up to do, particularly in our oceans. There is also still ice and snow to melt on some high mountains. The land and oceans need an extra month or two to warm up after the cold of winter. Soak it in folks! -Meteorologist Viki Knapp