Comment by gnicholas

Good point! During times when AC or heat is running a lot, there might be a bimodal distribution of reported temperatures. I wonder if they could use the ambient light sensor to determine if the person is inside or outside, or if they could use location data to figure out that 'this Apple Watch is in the middle of a large field, so he must be outside'. Then they could just ignore other data in that microclimate area, and create a weather mapping based on watches located in known open areas.