I figured out how to do it. It involves getting a free account at IFTTT.com, enabling the IFTTTrigger skill in Alexa, adding IFTTTrigger 1 and 2 as devices in Alexa, linking AlexaActionsByMkzense Service to IFTTT, creating 2 applets in IFTTT.com
https://www.amazon.com/mkZense-com-LLC-IFTTTrigger/dp/B08M496VGB
IFTTTrigger-1 turns off Smart Plug when less than 15 degrees F outside
IFTTTrigger-2 turns on Smart Plug when greater than 15 degrees F outside