We had a mild summer in Tennessee and my jalapenos were a crap shoot. Some of them got super hot. I grew 3 TAM mild plants, which were good and mild. The other regular jalapenos were great, but a few here and there were "sweat under your eyelids" hot.
I'm also a big fan of letting them turn red before harvesting. We've had a cold snap hit, so I'm gonna go get the last of them today. It was a great long harvest this year.