Why is the longest day not the hottest?

Question

Typically, the hottest days of the year are a month to a month and a half AFTER the solstice. Same with winter, the coldest are a month to month and a half after the solstice.

Just curious as to why the longest day under the heat lamp isn't the hottest?

Answer 1

Its simple. When the summer starts, the earth's surface and water temperatures are not at their highest levels. After the cool down of the winter, it takes a every long time for the earth's surface and water areas to warm up again. For instance, where I live, when its the first day of summer, the water temperatures are around 55 degrees, but in August they are around 72-75 degrees. So, as the summer progresses, water and surface temperatures will rise until the beginning of september, and then they will cool down. That is why the hottest days of the summer are usually around the middle of July to the middle of August. At those times, since the earth's surface and water temperatures are already near its peak, it makes it easier for the sun to heat things up.

That is why in August and the end of July you can have a low of 70 degrees but a high of 110. But that can't happen of the longest day of the year.

Answer 2

Because the Sun does not directly heat the air, at least not very much.  The air is heated more by the warm ground it is in contact with.  There is a lag time between when the incoming solar radiation reaches and is absorbed by the ground, and when the ground responds to that absorption by heating up.  Likewise, that is why the warmest time of day is not at noontime, when the Sun is at it's highest in the sky, but in the mid to late afternoon.