Metro had its first cracked rail of 2013 Wednesday morning as a cold snap kept the area shivering.

The crack outside the Green Line's Naylor Road station happened around 8:30 a.m. and gave riders 10-minute delays as trains single-tracked around the problem, Metro spokesman Dan Stessel said. Crews repaired the rail, which is outdoors, by 10:20 a.m. Metro sensors detected the problem before any trains passed over it, Stessel said.

Rails crack when subjected to cold weather or swings in temperature, since metal expands in warm temperatures and contracts in cold, and can be dangerous since trains going over them can derail. The Washington area is expected to reach a high temperature of only 26 degrees Wednesday.

"Cracked rails are not a surprise given the weather," Stessel said.

The crack was Metro's first for 2013. It had 28 cracked rails in 2012 and 49 in 2011.