Metra is reporting wire problems at the 63rd Street station in Chicago are significantly delaying trains on the Metra Electric and South Shore commuter rail lines in both directions.
It is unclear when the issues may be resolved, according to a message on the Metra Web site.
Metra also issued an online, system-wide alert about train delays due to the extreme heat.
"Due to the forecast for extremely hot weather in the Chicago region over the next several days, Metra riders may experience delays of 10 to 15 minutes," the alert reads. "When temperatures exceed 95 degrees, it is necessary to operate our trains at reduced speeds to compensate for heat-related stresses on our track, switches and signals. During this heat event, we will have all resources on standby so we can quickly respond and restore service. We regret any inconvenience this may cause."