The switching behavior and the magnetization states of non-interacting Supermalloy (Ni79Fe16Mo5) nanomagnet arrays were studied by magnetic measurements and micromagnetic simulations. The switching-field distribution of the easy-axis hysteresis loop of the nanomagnets was broadened due to lithographic shape variations and thermal fluctuations. When cooled to a low temperature (100 K), the switching-field distribution of the loop was reduced and its squareness ratio became higher. We found strong remanent magnetization along the hard axes of the nanomagnets, indicating the presence of metastable states and end-domain states. An oscillating field with amplitude of 30 Oe was sufficient to destabilize these metastable states; however, a high oscillating field (amplitude > 250 Oe) is required to reduce the remanence to zero.