Metrolinx says the soaring temperatures on Tuesday will once again impact service on some GO trains as well as the UP Express.
Two Kitchener line trips and four UP Express trips will not be running between 1 p.m. and 3 p.m.
Some trips on these lines may also see delays of up to 10 minutes due to heat related speed restrictions throughout the afternoon.
The cancelled trips and slow downs are necessary because the heat causes steel train tracks to expand which can ultimately increase risk of derailment.
To ensure safety, Metrolinx staff will be on “heat patrol,” monitoring track temperatures closely to adjust train speeds as needed.
Real-time service updates are available on the Metrolinx and UP Express websites.