It’s really hard to say. The record high//low temps in Texas are nearly 90 years old...well before any of the modern weather influences were known. Also, the planet has been going through climate changes for billions of years and modern record keeping only goes back 150 years or so.
15,000 years ago, most of Canada and the northern US was covered in a glacier a mile deep. It carved the Great Lakes.
Texas Temperature Records
- Hottest temperature ever recorded: 120 F, Seymour, northwestern Texas, 8/12/1936
- Coldest temperature ever recorded: -23 F, Seminole, western Texas, 2/8/1933