With the outbreak of World War II, immediately after the establishment of the airfield, the airport was taken over by the RNZAF to serve as a training base which became RNZAF Station Onerahi. Flight Lieutenant "Lou" Gates became one of the station commanders. Pilots practised bombing raids on the nearby Matakohe Island and Rat Island. The airport was established with three grass runways. No. 20 Squadron RNZAF was formed there in August 1942 with Hawker Hind biplanes, personnel and aircraft provided from No. 6 (AC) Squadron RNZAF at Milson, Palmerston North. The squadron was disbanded in July 1943 but reformed elsewhere later in the war. The station was reduced to two runways (06/24 and 32/14) shortly after the war and converted for public use. Some of the old airforce barracks are still present today, having been converted into residential properties.