As one of the few felids that is predominantly diurnally-active, cheetahs Acinonyx jubatus, in their natural habitat, are exposed to high heat loads. Whether they are at risk of hyperthermia is not known, because long-term measurements of body temperature never have been reported for cheetahs. We measured body temperature and locomotor activity with implanted data loggers over seven months in five free-living cheetahs in Namibia. Air temperature ranged from -2ºC in winter to a maximum of 39ºC in summer. The cheetahs displayed higher maximum 24 h body temperatures (~0.4ºC), peaking later in the day (~1 h), with larger fluctuations in the amplitude of 24 h body temperature rhythm (~0.4ºC) during a hot-dry period than during a cool-dry period. When ambient temperatures were high cheetahs shifted from a diurnal to a crepuscular activity pattern, with reduced activity between 9:00 and 15:00 and increased nocturnal activity. Yet, when a hunting opportunity presented itself, cheetahs hunted in the midday heat (air temperature 33.6ºC), and in total darkness (new moon). Although cheetahs were proficient in total darkness, the nocturnal activity was higher on moonlit nights than dark nights. Overall hunting success rate (derived from body temperature and activity profiles characteristic of hunts) was 38 ± 15%, similar to that reported for cheetahs previously. Our cheetahs coped well under high heat loads. They were opportunistic in their hunting strategy, hunting when they encountered prey rather than selecting preferred conditions in which to hunt.