Knowledge of spatial and temporal variability of soil moisture is critical for site specific irrigation management at field scale. However, installation feasibility, cost and between-sensor variability restrict the use of many point–based sensors at field scale. Active heat pulse method with fiber optic temperature sensing (AHFO) has shown a potential to provide soil moisture data at sub-meter intervals along a fiber optic cable to a distance >10000 meters. Despite the limited number of studies on soil moisture measurement using AHFO, this study evaluated the feasibility of AHFO to provide soil moisture data at sub meter (spatial) and diurnal to seasonal (temporal) scales in a subsurface drained field. Heat pulses of five minutes durations were applied at a rate of 7.28 Wm-1 through six fiber optic cable transects installed at three depths (0.05, 0.10 and 0.20 m) at six hours interval in a day. A distributed temperature sensing (DTS) instrument was used to estimate the cumulative temperature increase (Tcum) at locations along the cable. Indirect relationships between Tcum and soil moisture was developed and validated for each depth using the soil moisture measured by the commercial point–based sensors (calibrated by the gravimetric method). Sigmoidal (logistic) relationship provided the best fit between soil moisture and Tcum for the three depths with R2 values of 0.89, 0.91 and 0.91 respectively. In comparison to the calibrated commercial soil moisture sensors, AHFO showed predictive accuracies; RMSE of 3, 4 and, 4 % for 0.05,0.10 and 0.2 m depths, respectively. Further, it showed strong agreement between AFHO predicted and commercial sensors measured soil moisture values; correlation coefficient (r) of 0.87, 0.46 and 0.86 for the three depths, respectively. Results of this study showed the capability of AHFO method to provide soil moisture data at sub-meter intervals (spatial) along the fiber optic cable transects and diurnal to seasonal scales (temporal) with satisfactory accuracy.