Abstract: Methods and apparatus are provided for distributed temperature sensing along an optical waveguide disposed axially with respect to a conduit using a distributed temperature sensor and an array of temperature sensors. An exemplary method includes performing distributed temperature sensing (DTS) using two ends of a first optical fiber disposed within the conduit and having a return path coupling the two ends, performing discrete temperature sensing based on measured reflections of light from reflective elements having characteristic wavelengths disposed at discrete locations, and determining temperatures at a plurality of locations based on the DTS and the discrete temperature sensing.