Changes in ambient temperature and solar radiation may affect sloths’ metabolic rate and body temperature, with consequent changes in activities, postures and microhabitats selection. The synergistic effect of temperature and solar radiation on behavioral aspects were never systematically evaluated on field conditions. Here we evaluated the influence of hourly ambient temperature variation on maned sloth (Bradypus torquatus) activities, postures, and tree crown positions, under sunny and cloudy conditions; and tested if any of the animal posture and position increase their exposure to human detection. We performed 350 hours of visual observation on eight maned sloths in northern Bahia, recording their activities, and their resting postures and positions on tree crowns. We also recorded the time taken to visualize the sloths on 58 days. Higher ambient temperature increased the sloths’ activity levels in cloudy conditions, but reduced their activity in sunny conditions. Increasing ambient temperature also reduced the frequency of huddled posture and increased the frequency of extended posture and permanence in the inner tree crown. Lastly, the postures and positions did not influence sloths’ detectability. Our results on temperature-activity association in maned sloth suggests a dependence on other weather conditions, and systematically show that the individuals rely on resting postures and positions to thermoregulate. The warmer and drier future climate, expected to occur in the northern Atlantic Forest, may impose change in the diurnal activity levels and postural pattern for this threatened species.