@Florence, I don't think there is a gauge for the inside cabin temperature... The outside temperature you see should be the actual current temperature for your location, if you have LIVE weather selected. Otherwise, it will be what is set in the MSFS Weather Preset screen you currently have selected, which will normally be the Standard ISA temperature (15C at sea level). The OAT should drop by about -2C for each 1,000 ft. of altitude above sea level.