Peter Sinks, Natural limestone sinkhole in Bear River Mountains, Utah.

Peter Sinks is a large bowl-shaped depression in the Bear River Mountains in northern Utah. The formation stretches roughly half a mile wide and one mile long at an elevation of about 8,200 feet.

Utah State University student Zane Stephens identified the site's meteorological importance in 1983, and with the Utah Climate Center installed instruments in the valley in winter 1984. On 1 February 1985 Peter Sinks fell to −69.3 °F (−56.3 °C), the lowest temperature recorded in Utah and the second-lowest in the contiguous United States after Rogers Pass, Montana (−69.7 °F in 1954). Stephens reached nearby Middle Sink with Burns Israelsen to read the temperature himself, flew into Peter Sinks by KUTV helicopter with meteorologist Mark Eubank, and state climatologist Gayle Bingham confirmed the reading; the alcohol thermometer was sent to the Bureau of Standards in Washington, D.C.

The name comes from the two depressions that make up the site, called sinks locally. Since 1985 Zane Stephens and Tim Wright have run temperature studies here with Campbell Scientific weather equipment, tracking how cold air pools in the basin. On 1 February 1985 Stephens reached Middle Sink with Burns Israelsen to read the thermometer himself, and the instrument was later sent to the Bureau of Standards in Washington, D.C. for confirmation.

The basin has no valley outlet, so cold air settles at the bottom; expect the floor to be far colder than the rim. U.S. Route 89 runs through the North Sink just east of Peter Sinks, giving road access to the area. Ground cover is mostly soil, shrubs, grasses and rocks, with no trees to block the way.

The basin floor remains free of trees while its edges are forested – a reversed pattern compared to normal mountains. This unexpected distribution arises from extreme cold conditions that form at depth and prevent tree growth.