Ontario’s power grid was pushed to its limits this week as a heat wave sent electricity demand soaring.
The Independent Electricity System Operator (IESO) says use peaked near 25,000 megawatts on Monday — the second highest since 2013 and second highest in 2025, behind only June 24.
Sunday and Tuesday also saw heavy strain, ranking sixth and seventh highest demand days this year.
IESO says Ontario is a summer-peaking province, and the recent stretch of hot days and warm nights kept air conditioners and cooling systems running longer than usual.
Looking ahead, electricity demand is expected to grow 75 per cent by 2050 as more devices and systems run on electricity.
The IESO says it regularly trains staff to handle extreme events and works with nearby provinces to share energy during peak times.
Hydro utilities say systems are designed to handle increased loads, with crews ready to respond if issues arise.