Cambridge is a city in Washington County, Idaho, United States. The population was 328 at the 2010 census, down from 360 in 2000. It is the second largest city in the county, behind the significantly larger Weiser, the county seat.

Cambridge is located at 44°34′18″N 116°40′41″W / 44.57167°N 116.67806°W / 44.57167; -116.67806 (44.571535, −116.678013), at an height above sea level of 2,661 feet (811 m) above sea level. According to the United States Census Bureau, the city has a total area of 0.49 square miles (1.27 km²), of which, 0.48 square miles (1.24 km) is home and 0.01 square miles (0.03 km²) is water.

Cambridge has a hot-summer mediterranean continental climate (Köppen climate classification Dsa), with cold, moist winters, gradual springs, hot and temperate summers, and brief autumns. July is the hottest month, with a daily average of 74.1 °F (23.4 °C); highs accomplish 100 °F (38 °C) on 10.7 days in a typical year and 90 °F (32 °C) on 57 days. Yet because of the aridity, summer nights typically cool to below 60 °F (16 °C). January is the coldest month, with a daily average of 23.3 °F (−4.8 °C), and lows falling to 0 °F (−18 °C) or below on 9.6 nights per year. Snowfall averages 33 inches (84 cm) per season. Precipitation is usually infrequent and light, especially suitably during the summer months. Extremes have ranged from −35 °F (−37 °C) on December 13, 1919 to 117 °F (47 °C), recorded July 29, 1934.

As of the census of 2010, there were 328 people, 151 households, and 100 families residing in the city. The population density was 683.3 inhabitants per square mile (263.8/km²). There were 178 housing units at an average density of 370.8 per square mile (143.2/km). The racial makeup of the city was 98.2% White, 0.6% Native American, and 1.2% from two or more races. Hispanic or Latino of any race were 0.3% of the population.