A desert lizard that wants dry air
Uromastyx come from some of the hottest, driest rocky deserts on earth, across North Africa and the Middle East, and their humidity needs are the lowest of any common pet lizard: roughly 10-30%. This is the one popular reptile for which the beginner instinct to mist and humidify is exactly backwards. A uromastyx enclosure runs a basking spot around 120 degrees Fahrenheit, and air that hot, moving through a well-ventilated enclosure, stays dry almost by itself. Most of the animal's water arrives in its food, since wild uromastyx eat moisture-bearing desert plants, flowers, and seeds and may rarely drink at all. If you are choosing between desert species, this is the one whose care sheet reads like a warning against damp.
Where excess humidity causes harm
Persistently humid air in a uromastyx enclosure is linked to the problems keepers fear most in this genus: respiratory infections in an animal built for parched air, and skin and tail trouble where moisture sits against the body in burrows and hides. The spiny tail that gives uromastyx their name is used to plug the burrow entrance against predators, and it suffers in soggy substrate. A uromastyx that is gaping away from the basking spot, blowing bubbles, or leaving its tail dark and limp needs a reptile vet, and the keeper should bring the enclosure's humidity readings to that appointment, because they are usually part of the story.
Ventilation and heat do the moisture control
You control uromastyx humidity mostly by subtraction. Use an enclosure with real airflow, front or top ventilation that actually exchanges air, and avoid covering vents to trap heat, since the powerful basking lamp should do the heating on its own. Choose dry substrates such as a soil and sand mix kept dry, and keep the water bowl, if you offer one at all, small and on the cool end so it does not evaporate into the hot zone. A digital hygrometer on the cool end gives the honest reading; the air beside a 120-degree basking spot will always read near zero and tells you nothing. Homes in humid climates sometimes need the enclosure in an air-conditioned room to hold the range through summer.
The one exception: a slightly damper retreat
Many experienced keepers offer one hide, usually the burrow the lizard digs or a hide box at the cool end, where the air runs a little more humid than the open enclosure, giving the uromastyx the choice it would have in a deep desert burrow while the habitat overall stays dry. That microclimate is a nuance for settled animals, not a beginner requirement, and it never means wet substrate. The rule to shop by is simple: if your home cannot keep a hot, ventilated box dry, choose a different lizard. When your uromastyx travels or boards, KinsLe's Pet Passport carries its heat and humidity specification with its records, so nobody helpfully adds a mister to a desert animal's holiday setup.