Sure it’s been hot, but Thursday marks the “official” start of Summer

On May 10, Huntsville reached 90 degrees for the first time in 2018. Unfortunately, the thermometer hasn’t taken much of a break from reaching the 90s since then!

In fact, temperatures soared to 95 degrees just a few days later (May 14), and a total of 9 days within May featured 90+ degree heat.

The heat has been relentless in June. Out of the first 20 days of the month, 15 of them (or 75%) have reached 90 degrees or above at the official reporting station in Huntsville’s International Airport. Four of those days reached 95+ degrees (the hottest being June 15, when thermometers reached 96.) This is a tad above the average high for mid-June, which is climatologically in the upper 80s.

With nearly a month and a half of sweltering heat already, it can come as a surprise that summer hasn’t “officially” started yet, at least if you’re going by astronomical standards.

During the summer months, the northern hemisphere is pointed towards the sun. At the moment of the summer solstice, the earth’s tilt is oriented in such a way that the northern hemisphere has reached its maximum solar tilt.

This year, the summer solstice occurs on June 21 at 5:07 a.m. CDT.  On the date of the summer solstice,  the sun appears to be located directly overhead at noon at the Tropic of Cancer, which is located at 23.5 degrees north of the Equator (the 23.5 degrees is due to the Earth’s tilt on its axis). For reference,  Central Mexico as well as the Bahamas are located within the Tropic of Cancer.

This astronomical reference point for the first day of summer may seem “late” due to the building heat that begins in mid-May in Alabama. In addition, the date of the solstice can vary from year to year (from the 19th to the 23rd, depending on the summer vs winter solstice season). It can be hard to delineate seasonal data points of the first day of a season changes year to year, so meteorologists designate June 1st as the “meteorological” first day of summer for research purposes.