Matthew Scott Porter:
(Omaha (Nebraska), 14 July 1979).
American actor.
Porter made his breakthrough in 2006, with a recurring supporting role in As the World Turns. After a guest role in the pilot of Ugly Betty, Porter got the role of Jason Street in Friday Night Lights.

If any of you have ever lived down south of the Mason-Dixon line, you know that late September still means summer heat.

It’s saying that:
– People who have lived in the ‘southern U.S.’ (below the ‘Mason–Dixon line’) already know that
– Even in ‘late September’, it can still be ‘very hot’, like summertime.
🧾 Origin:
I ‘can’t reliably identify the exact origin’ (the specific book/article/post and author) from just this one sentence alone.
This kind of line is:
– commonly used as a ‘general regional remark’ (Mason–Dixon reference is widely used),
– and it may appear in multiple places (essays, articles, quotes, social media, or even misquoted sources).
✍️ Author:
Since the exact source isn’t confirmed, I ‘can’t name the author’ without risking misinformation. Scott Porter is mentioned but there is no solid proof he wrote this.