Here are my test results at 82°F ambient temperature. Measurements at the center of the top of the head and the center of the tube:
0m - 82°F head, 82°F tube
1m - 101°F head, 88°F tube
2m - 111°F head, 97°F tube
3m - 116°F head, 102°F tube
4m - 125°F head, 104°F tube
4m30s - 132°F head...