Fall officially started up this past Friday at 3:02 pm central time. Scientifically, it's called the Autumnal Equinox where the amount of solar energy coming in from the sun is equal for both the northern hemisphere and southern hemisphere. Also, both day and night are approximately the same amount of time. This differs from say the Summer Solstice where the most amount of the sun's energy is focused over the northern half of the globe, so we have the warmest temperatures during the months we call Summer. For the Equinox, the solar radiation is not as focused in one area.
There is a bit of a natural lag from when Fall starts and when we really start to see those kinds of conditions with cooler temperatures during the day and night. The Earth takes awhile to adjust to the different amounts of solar energy and thus the weather patterns take several days.
Speaking of cooler temperatures, they are on the way this week as a cold front moves in from the northwest. This weekend I've been showing the extreme difference in temperatures across the country from one side to another. It's baking out east, while across the west, they are feeling the first impacts of Fall. Even some snow has fallen across some of the mountain ranges.
The cold front arrives Tuesday switching up winds to out of the north along with some showers and thunderstorms. Temperatures will top out on Tuesday around 80° and then really drop by Wednesday and Thursday into the 70s.
Overnight lows will be in the 50s most likely starting on Thursday morning.
I know allergy sufferers have been dealing with symptoms lately, so hopefully some rain and cooler temperatures will help us out this week.