RTO-Wide Hot Weather Alert Issued for Aug. 21–22


PJM has issued a Hot Weather Alert for its entire region serving 13 states and the District of Columbia for Aug. 21–22 ahead of expected 90-degree weather.

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 reach 90 degrees across the footprint, which drives up the demand for electricity.

As of Aug. 17, PJM expects to serve a forecasted load across the RTO of around 140,684 MW on Aug. 21 and 139,940 MW on Aug. 22.

The forecasted summer peak demand for electricity is approximately 156,000 MW, but PJM has performed reliability studies at even higher loads – in excess of 163,000 MW.

PJM’s current peak demand for this summer occurred July 27 and was 148,000 MW. The all-time recorded peak electricity demand on PJM was 165,563 MW on Aug. 2, 2006.

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.