This study measured the variation over time of the creep strain fields around a fatigue crack tip in a single crystal Ni-based superalloy in an open environment at temperatures up to 900 °C using digital image correlation (DIC). A high-temperature DIC measurement system was developed to overcome three difficulties: the degradation of random patterns, thermal radiation, and heat haze. Tension hold was applied to the specimens, and the time evolution of the creep strain fields around the crack tip was measured at different temperatures and under different loading conditions. The proposed DIC system measured the short-term creep strain fields with high reproducibility and reliability, and the strain and strain rate increased as the temperature and hold load increased. To confirm the utility of the measurement results, the stress distribution around the crack tip was calculated using the finite element method (FEM), and the calculation results were validated by comparing the calculated strain to the measurement results. The effect of creep deformation on the fatigue crack propagation (FCP) is discussed.