The temperature in your reptile's terrarium will depend on the species of reptile you have. However, as a general guideline, most reptiles require a temperature gradient within their terrarium. The cool side of the terrarium should be around 75-85°F (24-29°C), while the warm side should be around 85-95°F (29-35°C). It's important to research the specific temperature requirements of your reptile species to ensure they are kept in a suitable environment.