Summer's beginning (June 21, 1:16 p.m.)

Definition and Q/A from Old Farmer's Almanac web page on Summer Solstice

The word solstice comes from the Latin words for "sun" and "to stop," due to the fact that the Sun appears to stop in the sky. The Sun is directly overhead at its most northern point at "high-noon" on the summer solstice, creating more sunlight in the Northern Hemisphere on this day then any other.
On the solstice, we also hit the longest day of the year. From here on out, the days begin to get shorter.

Question: Why isn’t the summer solstice, the longest day of the year, also the hottest day of the year?
Answer: The reason why July and August are generally hotter than June, the month containing the summer solstice, is that it takes a while for Earth to heat up. There is a lag time between sunlight being produced and it actually hitting Earth. Earth’s surface and atmosphere continue to receive energy from the Sun, even though the minutes of daylight are decreasing, and average temperatures will continue to rise until the Sun’s position in relation to Earth lowers and sunlight is hitting Earth less directly. That’s why we are all holed up in our air-conditioned living rooms in late July rather than June.

Summer Folklore and Verse

Deep snow in winter, tall grain in summer.–Estonian proverb
When the summer birds take their flight, goes the summer with them.
If it rains on Midsummer's Eve, the filbert crops will be spoiled.–Unknown
One swallow never made a summer.
Easterly winds from May 19 to the 21 indicate a dry summer.
If there are many falling stars during a clear summer evening, expect thunder. If there are none, expect fine weather.