At less extreme temperatures, the unit can still operate but you may see performance issues. The laser output and receive gain will drift with temperature. As a result, you could see more or less than the normal dynamic range. Auto tests could take less or more time to run. If the backscatter drifts too high, the OptiFiber may miss finding splice events.
You can see the effect of temperature by running real-time trace and comparing the backscatter level to the 0 on the y-axis (which is the level measured at the factory). The level will slowly creep up or down over time, as the unit heats up.
Temperature should generally not have much effect on OTDR measurements.
*** Be careful of having your fiber end faces ice over when the air is freezing and moist!