Two climates inside one enclosure
A ball python cannot make its own body heat, so the enclosure has to offer it a choice of climates and let behavior do the regulating. The design is a slope from one end to the other: a warm zone where the floor surface inside the warm hide sits in the high eighties to low nineties Fahrenheit, falling away through a middle in the low-to-mid eighties, to a cool end in the upper seventies that the snake can retreat to after feeding or whenever it wants to slow down. That spread is not a luxury — digestion, immune function and shedding all run properly only when the snake can warm itself fully and then cool off at will. A python kept at one flat temperature will eventually show you the cost in refused meals and poor sheds.
Heat sources, and the thermostat rule that governs them
Belly heat suits this ground-dwelling species best: a heat mat under one end of the enclosure, or a radiant heat panel above it, warms the floor of the warm hide the way sun-warmed ground would. Whichever source you use, the rule that admits no exceptions is that it runs through a thermostat, with the probe placed where the snake lies. An unregulated mat can climb far past the safe range, and a ball python will sit on a surface that is burning it rather than move — keepers learn this the hard way, so learn it the easy way instead. Heat rocks are banned outright for the same reason. With the thermostat set and the probe at floor level inside the warm hide, check its reading against a second thermometer rather than trusting one instrument with a snake's skin.
Measuring where the snake actually lies
Most gradient mistakes are measurement mistakes. Air temperature read halfway up the glass tells you little; the numbers that matter are surface temperatures at floor level, taken with probe thermometers sitting in each hide and spot-checked with an infrared thermometer across the floor. Set the enclosure up with a hide at each end — genuinely similar hides, so the snake is not choosing between its favorite shelter and its preferred temperature — and a water bowl toward the cool end, where it doubles as a humidity source the snake can soak in before a shed. Then watch the snake use the space: a python that spends all its time at one end is giving you a reading too, usually that the other end is outside the range it wants.
When the gradient is wrong, and what it looks like
A snake permanently camped on the warm side may be telling you the room runs too cold overall; one that refuses food for weeks at a stretch may never be reaching proper digestion temperature; and one soaking constantly in its bowl is often too warm, or fighting mites, which is its own reason to investigate. Wheezing, mucus bubbles or open-mouth breathing point to respiratory infection and a vet visit, with temperatures reviewed as part of the fix. The daily habit that prevents most of this is unglamorous: eyes on both thermometer readings, every day, noting drift before it becomes a symptom. KinsLe's Care Teams holds that check as an assigned duty — whoever is on python duty records it, and the completed task carries its timestamp — so the gradient is verified on the days you are traveling, not just the days you are home.