I think you can get smoke as long the thermostat is set above the outdoor temperature. Probably the lowest practical setting is around 100F. If you want to cold smoke below that, just put together an add-on box with a duct between the CS top vent and the add-on - there's been some discussions in the past.
One tip: You'll get a lot more smoke at low temperatures if you chop up your chunks of wood into 1/8" to 1/4" sticks. You can also use sawdust or shavings by making a little loose foil packet of them to put in the wood box.