SAN FRANCISCO (KRON) – Bay Area Rapid Transit is warning commuters to expect delays as trains travel at reduced speeds due to the heat wave scorching the region.

Delays are impacting the entire system as of midday Tuesday. While most lines are delayed only 10 minutes, there’s a 20-minute delay on the Antioch line in both the Antioch and SFO [San Francisco International Airport] directions.

The news of delays had started earlier Tuesday with a tweet stating some lines were delayed 10 minutes.

“There may be up to 10-min delays today in the Antioch, Dublin/Pleasanton, SFO [San Francisco International Airport] and Daly City directions,” a tweet from the transit agency stated. “Trains will be traveling at reduced speeds in some areas due to warm weather conditions.”

A train track that’d been warped due to the heat led to a BART derailment June 21 between the Concord and Pleasant Hill stations. Lowering speed will help prevent these kinds of derailments, the agency told KRON4 last month, when BART trains’ speed was lowered to 44 miles per hour due to the last heat wave.