When you enter a specific location, your Nest Thermostat will turn on to a certain temperature.
When you leave a specific area, try using this Recipe: www.ifttt.com/recipes/184048
This Trigger fires every time you enter an area you specify.
This Action will set a Nest Thermostat to the temperature you specify. NOTE: works only when Nest is set to Home.
Explore more great ways to automate
Nest Thermostat and Location