PJM Hot Weather and Max Gen Alerts: What Businesses Do

Ohio market insight · Capacity & grid

Updated September 27, 2026Ohio Commercial Energy editorial teamHow we review content Book a free 15-min bill review

The short answer

PJM warns the grid about stress in stages. A Hot Weather Alert (one to two days ahead) asks nothing of customers; a Maximum Generation Emergency / Load Management Alert (usually the day before) means demand response may be called; a Pre-Emergency or Emergency Load Management Reduction Action is the call itself; voltage reduction and rotating outages are last resorts. For a business, the alerts are triggers: prepare on a Hot Weather Alert, stage your load-reduction plan on a Max Gen alert, and execute when demand response is dispatched or your capacity-tag alert service says a peak hour is likely.

This page covers the alert types and a decision plan for each. For facility operations during a heat emergency and rotating-outage readiness, see heat-emergency operations; for using peak days to cut your capacity tag, see the PLC playbook; for what demand response pays, see demand response earnings; and for the underlying reliability concepts, see grid reliability explained.

The alert ladder

PJM's emergency procedures escalate from advance notices to real-time actions. The ones that matter most to a business in summer:

PJM message	When it's issued	What it means	Customer action required by PJM?
Hot Weather Alert	1–2 days ahead of forecast 90°F+ temperatures and/or high humidity	Grid operators and generators prepare for high load	No
Maximum Generation Emergency / Load Management Alert	Typically the day before	All generation may need to run at maximum; demand response may be deployed	No, but enrolled demand-response sites should expect a call
Pre-Emergency / Emergency Load Management Reduction Action	Real time, with lead time set by the program	Demand response is dispatched in named zones or the whole footprint	Yes, for enrolled demand-response sites
Energy Emergency Alert (EEA) levels 1–3	Real time	NERC's scale: all resources in use (1), load management in use (2), firm load interruption imminent or in progress (3)	Watch for utility instructions
Voltage Reduction Alert / Action	Alert ahead; action in real time	Distribution voltage lowered a few percent to reduce load	No, but sensitive equipment may notice
Manual Load Dump (rotating outages)	Real time, last resort	Utilities interrupt circuits in rotation, generally 15–60 minutes each	Service interruption

PJM also issues localized messages — for example, a Post-Contingency Local Load Relief Warning when a specific transmission element is stressed. Those can lead to local load shedding even when the region as a whole has enough supply, as central Ohio experienced after severe storms in June 2022.

How often this happens now

June 23–25, 2025: PJM load reached 160,526 MW on June 23, its highest since 2011. PJM issued Maximum Generation and Load Management Alerts, declared NERC EEA Level 1, and called pre-emergency demand response across the entire footprint on June 24.
July 1–3, 2026: PJM set a new all-time peak of about 168,158 MW on July 2 (5–6 p.m.), beating the 2006 record of 165,563 MW. It deployed roughly 6,100 MW of demand response that day and about 5,000 MW on July 3. The U.S. Department of Energy issued two emergency orders, and PJM issued a warning that data centers and other large loads with backup generation could be asked to switch to it — a step that turned out not to be needed.
September 1, 2026: Pre-emergency demand response was called in several zones, including AEP.

With PJM's recent capacity auctions clearing below the reliability target, expect Max Gen alerts and demand-response calls to be routine in hot weeks rather than rare events.

Getting the alerts

PJM's emergency procedures page (emergencyprocedures.pjm.com) posts every alert and action as it's issued; PJM also publishes daily "hot weather operations" updates on its Inside Lines news site during events.
Your curtailment service provider (CSP) sends dispatch notices if you're enrolled in demand response — these are the ones with contractual consequences.
Your supplier or broker may offer a peak-hour forecast service aimed at capacity tags. These are forecasts, not PJM messages; PJM identifies the five tag-setting hours only after the summer ends.
Your utility communicates conservation requests and outage information; make sure your account contacts are current.

Route all of them to at least two people per site, including someone on the evening shift.

What to do at each level

Hot Weather Alert — prepare.

Confirm staffing for the next two days and name the person authorized to reduce load.
Check that pre-cooling schedules, setpoint limits and load-shed sequences are loaded in the building automation system.
Verify backup generators, fuel and transfer switches at sites that depend on them.
Postpone non-urgent start-ups of new equipment and generator tests that would transfer load back to the grid during the afternoon.

Max Gen / Load Management Alert — stage.

Enrolled demand-response sites: confirm with your CSP, walk through the curtailment sequence, and make sure your committed reduction is actually available tomorrow.
Tag management: treat 2–7 p.m. on the alert day as a likely peak window. Decide in advance which deferrable loads — EV and forklift charging, batch processes, water heating, some HVAC stages, decorative lighting — you'll shift, and by how much.
Tell supervisors and customers anything that affects them (warmer set points, delayed deliveries).

Load Management Reduction Action — execute.

Enrolled sites must reach their committed level within the program's notice period and hold it for the event; underperformance reduces payments and can trigger penalties.
Log start and stop times and approximate kW shed; you'll need them to reconcile CSP settlements and to evaluate next summer's plan.

EEA 2–3, voltage reduction or rotating-outage warnings — protect.

Switch from cost management to continuity: follow your outage plan, protect refrigeration and IT, and keep life-safety systems untouched. The operating details are in heat-emergency operations and continuity planning.

Alerts and your capacity tag

Your capacity tag for June 2027–May 2028 is set from your load during PJM's five highest summer 2026 peak hours, which PJM confirms after the season. The July 2 record hour is almost certainly among them. Alert days and peak-tag hours overlap heavily, but they aren't the same thing: some alerts come on days that don't end up in the top five, and a peak hour can fall on a day with only a Hot Weather Alert. Businesses that manage tags usually respond on more days than the five that count — the cost of a false alarm is modest, and at about $119–$122 per kW-year through 2028/29 a missed peak hour is expensive. For what a kW of tag costs by account size, see capacity bill math; for the auction results behind those prices, see PJM capacity auction results; and for how the 2025 price jump first reached bills, see the 2025 case study.

FAQ

Does a PJM Hot Weather Alert mean I have to cut my usage?

No. PJM says a Hot Weather Alert requires no customer action. It's a signal to prepare, especially if you manage your capacity tag or are enrolled in demand response.

What is a Maximum Generation Emergency / Load Management Alert?

A day-ahead PJM notice that all generation may need to run at maximum output and that demand response may be deployed. Enrolled sites should be ready to curtail.

Will I get a warning before rotating outages?

PJM's procedures escalate through several steps first, but a transmission emergency can require fast local load shedding. Keep an outage plan that doesn't depend on advance notice.

Where can I see current PJM alerts?

On PJM's emergency procedures page and its Inside Lines operations updates. Demand-response participants also receive dispatch notices from their curtailment service provider.