Yes the cycle goes faster the hotter it is. And, cool weather slows them down. One year I checked outside in early spring to see how long it would take an egg to hatch in cold weather. It took 3 weeks. The eggs were okay. A friend said in the fall it took a chrysalis 6-8 weeks to hatch on her porch.
But, when it is hot the cycle can go super fast. I remember someone saying that they had adults out of chrysalis in 4 days.
But, they do have a threshold heat level of around 103 degrees. In nature the Monarchs will go down near the ground and under leaves to avoid excessive heat. In the fall when it is cold, I've seen them hanging out near rocks, which absorb heat and provide warmth during the cold nights. Below freezing temps will kill caterpillars and pupae. The adults can stand a few days of below freezing temps, if they are not wet.
Herndon, VA (USA)
Take care of the small things....