Weekly changes in adult Anopheles species were monitored at Camp Humphreys (CH), Ganghwa Island (GH), and Warrior Base (WB), from May–October, 2009–2010 to explore the relationship between Plasmodium vivax development and vector dynamics in the Republic of Korea (ROK). Adult females were trapped and dissected to determine parity for estimating longevity, mortality, and birthrate. A degree-day (DD) method was used to estimate the extrinsic incubation period (EIP) of P. vivax and duration of the gonotrophic cycle and other life stages. Anopheles sinensis was the predominant species, with satellite data showing peak abundance occurring after the period of maximum greenness. Abundance peaks were location dependent, comprised nulliparous and parous females, and timing could not be fully explained by DD estimation. Parity showed synchronicity between locations and years and was highest for September and lowest during maximum greenness. Mosquito longevity was predicted to exceed the EIP (when malaria transmission is possible) during weeks 29, 31, 34, and near the end of the season. Area-wide changes in parity suggest a common cause; information on local larval habitat and agricultural practices may explain location-specific effects. DD estimates of EIP and parity could be used to predict when conditions are suitable for P. vivax transmission.