[Alan Roehrich]

Fairly common. It depends upon how much a given engine is affected be weather, and how well it is tuned for prevailing conditions. The more torque is lost due to weather, the more the stall RPM drops. People that have to race heads up often change the converter and the rear gear for the weather. I have customers who have a "Denver converter" they swap in. Or a "heat of summer sticky weather converter".