When chilies burn in our mouths, the surrounding temperature does not affect how hot the taste of the chilli is. It is only the spiciness that we taste in our mouths. This spiciness is caused by the chemical called capsaicin. This chemical is contained in the cells of the chilli. Capsaicin irritates the cells in your mouth so that is why you feel the discomfort in your mouth.
Hope it helps :)