 Dunnigan is located 11 miles (18 km) from Arbuckle and nearly 40 miles (64 km) from Vacaville and Sacramento.According to the United States Census Bureau, the community is approximately 5.2 sq mi (13.2 km²); all land.According to the Köppen Climate Classification system, Dunnigan has a hot-summer Mediterranean climate, abbreviated "Csa" on climate maps.