On Jul 23, 9:12*am, Home Guy wrote:
*I have a temperature sensor mounted about 1" under the plywood
roof deck in the attic and it went from about 120F to about 100F during
the watering.

The temperature at this point may be misleading (most affected by the
sun, least affected by venting). Repeat the experiment with the sensor
on or near the ceiling insulation, half way between the peak and an
outer wall.