not sure if that line is electrified (I do know between DC and B'more is because those are Amtrak tracks) but the overhead wires can have issues when it gets 100F+. Also the rails can get warped.
Metro will prob be running reduced speeds above ground today.
DCA, along with likely logging another 97+ day, has been hanging around 107-110 for the heat index most of the day.
Here, our dewpoint has been around 80F all day - it's literally arresting when you step outside.
Lol there is a video of Trudeau going for a run on the Mall at around 7am this morning (DCA was 84/75 at that moment) - hope my dude brought some water.