The heat came in fast and fierce to PJM – for some, at least. But for those using Amperon’s forecasts, you knew well in advance that high demand days were on their way. The June heat wave that swept from the Northern Plains to the East Coast was no ordinary event. An upper-level high pressure system over the Ohio Valley locked in extreme temperatures for days, and overnight cooling was minimal. As a result, demand soared — and so did market volatility.

On June 23, 2025, the PJM grid hit 160.2 GW during Hour Ending 18 (HE18), the highest demand in over a decade. That’s well above the 154 GW PJM forecasted for this summer’s peak — and it’s only June.

But if you were using Amperon’s forecast, this surge wouldn’t have caught you off guard. In fact, you could have made trades as early as seven days out with full confidence the grid was about to get tested — and real-time prices would follow. However, if you were relying on PJM’s forecast, you would have been too late. Seven days out from the 23^rd, PJM was only forecasting peak demand to reach about 155 GW, where Amperon’s insights would have informed you that demand would surpass this by at least 4 GW on the same day.  

Weather Analysis: Why the Grid Was Stressed

A major heat wave began last weekend and intensified as high pressure stayed over the Midwest and Eastern U.S. The heat moved from the Northern Plains into the Midwest and Great Lakes, then spread to the East Coast through Wednesday. An upper-level high over the Ohio Valley remained in place through Tuesday, leading to widespread Extreme Heat Warnings and Heat Advisories. Clear skies, light winds, and very warm days and nights made it hard for temperatures to cool down overnight, increasing the risk of heat-related issues. Many daily temperature records were broken across the region.

Forecast Evolution Over The Week

On June 16, Amperon forecasted a 159.8 GW peak for June 23, which ultimately reached 160.2 GW, the highest demand in over a decade. For June 24, our models were calling for 158.2 GW as early as June 16 at multiple intervals — well before PJM caught up. In fact, on June 17 at 12:35 PM CDT, Amperon was forecasting 158.9 GW, while PJM was still sitting at 154.8 GW. It wasn’t until June 19 that PJM finally revised its forecast closer to ours, while Amperon had already increased its projection to 161.4 GW.

It is important to note, these are the HE18 predictions 14-0 days before (every iteration) for every weather vendor.  

Both evenings saw very negative DARTs due to new net load peak records, and real-time prices soared past $3,000/MWh. Western Hub Daily DA Peak Fixed futures for June 23 jumped from $131.60 on June 16 to $165 by June 17, and reached $175 by June 19. Traders using Amperon’s forecast could have made strategic trades a full week ahead of time —  capitalizing on price movement well before the rest of the market caught on.

Accuracy Call Outs

• On June 23, Amperon’s APE at the peak hour (HE18) was 0.46%, and our MAPE for the day was 1.13%, compared to PJM’s 1.48%.

• On June 24, our APE at HE18 was just 0.23%, and our MAPE was 0.72%, less than half of PJM’s 2.09%.  

• In both cases, Amperon correctly predicted the peak hour (HE18), while PJM missed it by one hour, forecasting HE17.

It's only a couple of days into the official start of summer and we already blew past PJM’s summer peak forecast. With August still ahead, this could easily happen again. If you’re not using Amperon’s forecasts, you’re not just behind—you’re missing opportunities. Energy was still trading around $131/MWh on June 16 in Western Hub, but jumped to $165 by June 17, and continued rising from there. Our demand forecasts, which go 15 days out, create clear opportunities to buy low and sell into a tightening market — translating to significant upside for those positioned ahead of the curve.

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