PJM has issued a Hot Weather Alert for its Western Region for Monday, Aug. 26, in anticipation of hot and humid weather building through the week in the Midwest.
A Hot Weather Alert helps to prepare transmission and generation personnel and facilities for extreme heat and/or humidity that may cause capacity problems on the grid. Temperatures are expected to go above 90 degrees, which drives up the demand for electricity.
Electricity use for the entire PJM region is currently expected to peak just above 138,000 MW on Monday.
The highest preliminary peak load that PJM has served so far this summer was approximately 153,400 MW and occurred on July 16. PJM’s all-time, one-day highest power use was recorded in the summer of 2006 at 165,563 MW. One megawatt can power about 800 homes.
The Western Region in PJM is made up of the following transmission zones and control areas:
- American Electric Power (AEP Ohio, Appalachian Power, Indiana Michigan Power and Kentucky Power)
- American Municipal Power Transmission
- ComEd
- Cleveland Public Power
- Dayton Power & Light
- Duke Energy Ohio and Duke Energy Kentucky
- Duquesne Light Company
- East Kentucky Power Cooperative
- FirstEnergy South – former Allegheny Power Systems (West Penn Power, Mon Power, Potomac Edison)
- FirstEnergy West – former American Transmission Systems, Inc. (Penn Power, Ohio Edison, The Illuminating Company and Toledo Edison)
- ITC Interconnection, LLC
- Ohio Valley Electric Corporation
Preparing for Hot Weather
PJM is prepared to serve the forecasted summer peak demand for electricity with approximately 185,000 MW of installed generating capacity available to meet customer needs. This includes sufficient resources available in reserve to cover generation that is unexpectedly unavailable or for other unanticipated changes in demand.
Last year’s peak demand was approximately 149,000 MW.
In preparation for summer, PJM has worked with transmission and generation owners throughout the spring to ensure that critical maintenance and system improvements were completed. To stay ahead of any fuel-related supply chain concerns, PJM continues to conduct fuel inventories every two weeks and monitors results for the generation fleet.
A dedicated team of operators uses sophisticated technology to balance supply and demand and direct the power grid 24/7 from PJM’s control rooms. They prepare multiple potential scenarios that could be impacted by weather, emergency conditions or equipment failure. They adjust resource output with changes in demand and ensure that no transmission lines or facilities are overloaded. The team also watches for unusual conditions and reacts to them to protect the electricity supply.
Read more about how PJM forecasts electricity demand on the PJM Learning Center.

