I read somewhere that the R-Pi 2 and R-Pi 3 are not used because of the heat they generate, they would not pass ESA standards for operating temperature. In reading this, I have set in my mind that the heat generated by these R-Pi units would interfere with the Sense_Hat sensors.
After building my AstroPi unit (3D Printed Plastic Case), i wanted to use one of my R-Pi 2 units but could not find one as the two I have are in separate projects. So I decided to use a spare R-Pi 3 unit I have. To keep things cool on the R-Pi 3, it has heat sinks on the CPU and I/O Chips. Assembling the AstroPi, it works great.
It works great until I did a modified scrolling_env.py program to sense the environment around it. Temperatures in NYC this past month while I made this AstroPi was in the low to mid 70s Fahrenheit. So I thought that it should be registering that as its temp. Instead it measured 85+ degrees. I ran the program a couple more times, and the temperature kept getting higher and higher. The highest temperature reading was 104.2 Fahrenheit.
I'm thinking to my self, "What's going on?"
Took the Astro Pi apart, and it was warm inside. The R-Pi 3 was hot but not burning hot, as the heatsinks were doing their job. Only thing I can figure out is that the R-Pi 3 issue with generating heat is interfering with the Sense_Hat's Thermometer. Did a few tests (like running the AstroPi Unit with its case open), and it confirms it - the heat created by the R-Pi 3 is interfering with the Sense_Hat's thermometer. It is also interfering with the humidity and barometric sensors as well but not as great as the thermometer.
Now to get a R-Pi Model B+ to replace the R-Pi 3 and see if this would works as it should.
Live and learn...