Snakes, being cold-blooded, thrive in warmer environments and generally prefer hotter conditions over cooler ones. A temperature of around 28°C is well within the comfortable range for most common pet snakes, allowing them to properly digest food, regulate their metabolism, and stay active. In contrast, 21°C is usually too cold as a primary ambient temperature for most species—it can cause sluggishness, suppressed appetite, weakened immunity, and increased risk of illness if they are kept at that temperature for long periods. Tropical species like ball pythons and boa constrictors do especially well in a gradient where the warm end reaches around 28–32°C, while temperate species like corn snakes still appreciate an ambient temperature closer to 24–28°C with a warm basking area. Because snakes cannot generate their own body heat, they rely on a thermal gradient that lets them move between warmer and cooler spots as needed. Providing a temperature around 28°C as part of this gradient will make most snakes more comfortable and help maintain their health, especially compared to a consistently cooler environment of 21°C. So, to sum up, most snakes will handle hotter conditions better and prefer a warm setup to a cold one, and an ambient of 28°C is generally preferable to 21°C.