Commuter railways across the D.C. metropolitan area have slowed their trains this week due to heat-related speed restrictions.

Transit officials said high heat can warp train tracks, which imperils safety and requires slowing trains.

When track temperatures reach 135 degrees Fahrenheit or higher, Metrorail slows above-ground trains to 35 mph across the entire system, the transit agency posted on X.

The speed restrictions on Metrorail were first put in place Monday after tracks outside Crystal City developed a kink in the line, officials said.

Trains on the Blue and Yellow Lines between the Crystal City and National Airport stations were single-tracked. The rail warp was fixed and regular service resumed Tuesday between the stations, but the heat did not abate.

The high temperature in the District was 104 degrees, the National Weather Service Baltimore-Washington Office posted on X. The high in Baltimore was 105 degrees.

MARC trains were slowed to 40 mph until 8 p.m. Tuesday. Virginia Railway Express also implemented speed restrictions, according to WRC-TV.

• Brad Matthews can be reached at bmatthews@washingtontimes.com.