Amtrak warned that high temperatures could force trains on the Northeast Corridor to be delayed by up to an hour into Sunday evening.
Extreme heat has blasted the Midwest and Northeast this week, with temperatures reaching the triple digits on the East Coast on Saturday and Sunday.
High temperatures make the steel tracks expand, raising the risk of derailments or other track failures. Lowering the speed of trains ensures safety.
The company said delays would slow and end around 7:30 p.m., as temperatures cooled.
Similar delays are common on commuter rail and subway services as well. The Washington Metro slowed trains from a maximum of 65 mph to 35 mph due to the heat, causing slower service.
The heat wave is expected to continue into this week, the National Weather Service forecast, with temperatures in the 90s predicted for much of the East Coast.
