And you're probably thinking: "It's just starting?? What about all this heat we've had the past month??"
Even though temperatures have been above normal for a month straight now, and it's been 94 or higher for eight consecutive days with no end in sight, the summer solstice officially takes place on June 21 at 6:28am CDT. So, while meteorological summer started on June 1 (and it seems more accurate this year given the weather), technically June 21 is the official first day of summer.
The solstice is the point in time when the Earth's axis is most inclined toward the sun, yielding the longest day of the year for the Northern Hemisphere, thus the beginning of our summer. It is also the day when the apparent position of the sun is the highest in the sky for those in the Northern Hemisphere. The graphic above shows the illumination of the Earth at the summer solstice. Notice that the areas around the Arctic circle get light all day as the Earth rotates, while those areas near the south pole are in darkness all day. So, even though we've already sweated through the month of June, welcome to summer!