Peter Sinks facts for kids

Peter Sinks is a natural sinkhole in northern Utah. It is known as one of the coldest places in the contiguous United States.

This special spot is located about 8,100 feet (2,500 m) high in the Bear River Mountains. This is east of Logan, inside the Wasatch-Cache National Forest. Peter Sinks gets extremely cold because of something called a temperature inversion. This means cold air gets trapped in the sinkhole at night. Even in summer, the bottom of the sinkhole often freezes. It gets so cold that trees cannot grow there.

On February 1, 1985, a temperature of −69.3 °F (−56.3 °C) was recorded at Peter Sinks. This was the lowest temperature ever recorded in Utah. It was also the second-coldest temperature recorded in the entire contiguous United States.

Peter Sinks: Utah's Cold Spot

Peter Sinks is a large, bowl-shaped dip in the ground. It's about half a mile wide and has no way for water or air to drain out. This makes it a perfect trap for cold air.

How Peter Sinks Gets So Cold

During clear, calm nights, the heat from the day quickly escapes into the sky. Cool, heavy air then slides down into the basin. This process is called "cold air pooling." It causes very low temperatures, especially after cold fronts in winter.

The climate here is like a subalpine or subarctic climate. This means it's usually very cold, even though it doesn't have the typical boreal forests found in such climates. The extreme cold stops these forests from growing.

Discovering the Cold

A Utah State University student named Zane Stephens first noticed how cold Peter Sinks was in 1983. Stephens and the Utah Climate Center put special measuring tools in the valley in the winter of 1984.

On February 1, 1985, Peter Sinks dropped to −69.3 °F (−56.3 °C). Another nearby valley, Middle Sink, also got very cold, reaching −64 °F (−53 °C). Stephens hiked into Middle Sink to check the temperature himself. He then flew into Peter Sinks in a KUTV television helicopter with meteorologist Mark Eubank. State climatologist Gayle Bingham also went there to confirm the temperature. The special thermometer used was sent to the Bureau of Standards in Washington, D.C. to make sure the reading was correct.

Studying the Sinks

Since 1985, Zane Stephens and Tim Wright have studied Peter Sinks and Middle Sink a lot. They use special weather equipment to learn more about these cold spots. On January 29, 2002, Middle Sink dropped to −62 °F (−52 °C).

Stephens and Wright mainly study how temperatures change within the trapped cold air. These valleys act like a dam, holding cold air. The coldest air sinks to the very bottom. They have found that the temperature difference between the cold air "lake" and the warmer air above can be as much as 70 °F (39 °C).