Ashburn sits in a humid subtropical belt: hot, muggy summers and cool winters, so the grid here works hard in both seasons. Below: live conditions, the 7-day outlook, and what it means for electricity demand on the PJM (Dominion zone) grid.
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High and low temperatures, with the implied heating and cooling demand below.
Ashburn is the heart of the world's largest data-center cluster, Northern Virginia's "Data Center Alley." These facilities run flat out year-round, so weather mostly moves the cooling load on top of an already huge baseline. A hot, humid stretch lifts air-conditioning and data-center cooling demand together, tightening the PJM Dominion zone exactly where load is most concentrated.
Summer is the binding season: PJM's Dominion zone hits its highest demand on hot July and August afternoons. Winter cold snaps matter too, but the cooling peak is the one to watch.
See live PJM (Dominion zone) grid data →They measure how far the day's average temperature sits from a comfortable 65°F. Cooling degree days (CDD) count degrees above 65 and track air-conditioning demand; heating degree days (HDD) count degrees below 65 and track heating demand. More degree days means more energy used to keep buildings comfortable, and a higher grid load.
Temperature is the single biggest short-term driver of electricity demand. Hot afternoons and cold mornings push load toward the grid's limits, which is when prices rise and reliability is tested. Watching the forecast is watching the grid's next few days.
Live weather and the 7-day forecast come from Open-Meteo. Degree days are computed from the forecast highs and lows against a 65°F base. Live grid data is on the PJM (Dominion zone) region page.