Accurate Altimeter: https://play.google.com/store/apps/details?id=com.arlabsmobile.altimeterfree&hl=en & Smart Thermometer: https://play.google.com/store/apps/details?id=com.colortiger.thermo&hl=en (also does humidity and air pressure).
Amazing Mobile Apps: Altimeter, Barometer and Thermometer: