We used satellite sea surface temperature data and aerial survey data to identify an upper (28 C) and lower (13.3 C) thermal limit to preferred loggerhead sea turtle temperatures. The available temperature range for the turtles to occupy, during this study (May 1991 to Sept. 1992), was 4.9 C to 32.2 C. These thermal limits fall within the ranges previously identified in the laboratory. This study suggests that sea turtles are not geographically randomly distributed but stay within preferred temperature ranges which are seasonally variable.