A temperature sensor includes a polymer body for mounting the sensor to a mounting surface and positioning a temperature sensing element within a target fluid. The temperature sensing element may be positioned at the distal end of the polymer body and may be sealed from the fluid by a metal cap filled with a thermally conductive material. In this manner, the polymer body may thermally insulate the temperature sensing element and lead conductors within the polymer body from the mounting surface. The polymer body may also include a connector on the proximal end to facilitate an electrical connection with the temperature sensing element, a flange to install the sensor against the mounting surface, and a fixation surface configured to mate with the mounting surface. In some examples, the polymer body may be constructed in two stages to facilitate different configurations of the connector, flange, and/or fixation surface.