A night‐time image of Nissyros from the ETM+ (Enhanced Thematic Mapper+) scanner onboard the Landsat 7 satellite was acquired in October 2000. The image was processed to compute surface temperature on the volcano while contemporaneous field measurements on the island's surface were collected. We confirm that the thermal sensor of Landsat 7 can map (a) the ‘orographic effect’ on land surface temperatures (temperature falling with increasing elevations) and (b) the crater surface temperature within an accuracy of 0.4–2°C. In addition, the low‐temperature fumarolic activity of the volcano could not be detected on the mid‐infrared bands (5 and 7). However, there are some high‐frequency temporal variations of surface temperature inside the main crater that cannot be mapped because of the revisit capability of the sensor (16 days).