HOUSTON – Ahhhh, the first day of fall. When the leaves start to change color, the temperatures cool down, and we can order a pumpkin spiced latte to warm our hands and hearts… But not in Houston. Temperatures in Houston are expected to be in the 90s for the next week. Which begs the question, why does fall officially start on a Sunday?

It is important to understand what the first day of fall really means. The autumnal equinox has nothing to do with temperatures. It has everything to do with the relationship between the earth and the sun.

On Sunday morning, September 22nd at 7:44 AM, the direct rays of the sun will hit the equator. This is a point in time that occurs worldwide when the sun is directly overhead. This is the autumnal equinox. The word equinox comes from Latin and means “equal night.” In Houston, we don’t get a perfect 12 hours of daylight and 12 hours of night on this day, but it comes close. Sunrise is at 7:10 AM and sunset is at 7:17 AM. What’s cool about Sunday is that the sun rises in the east and sets in the west.

The sun is not a point in the sky, but a disk. The scientific definition of sunrise, as defined by the United States Naval Observatory, is when the top of the sun is first visible (at sea level). Similarly, the definition of sunset is when the top of the sun sinks below the horizon. This difference gives us 2-3 more minutes of sunlight each day. The atmosphere also refracts or bends sunlight, causing the sun to appear on the horizon while it is still physically below the horizon.

IN SEARCH OF THE TROPICS: Stay up to date on the storm’s impact in the Houston area with these tools from KPRC 2

Equilux is the day closest to equal day and night. That day this year in Houston is September 26, when the sun is above the horizon for 11 hours, 59 minutes, and 56 seconds.

Thursday we reached a record high of 98° at the hottest part of the day. The previous record was 97° from 1995. Will we ever cool down? YES. Fall brings shorter days. In a month or two, our daylight will decrease by an hour. Not as much sun will result in cooler temperatures.

And we are also at that time of year where we are getting our first real cold front. A front that will drop temperatures into the 70s and lower humidity. It is not yet on the 10 day forecast, but it will arrive sometime in October.