New York City has a humid continental climate: hot, sticky summers and cold winters, with both seasons pulling hard on the grid. Below: live conditions, the 7-day outlook, and what it means for electricity demand on the NYISO grid.
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High and low temperatures, with the implied heating and cooling demand below.
Downstate New York is a summer-peaking, transmission-constrained pocket. Hot, humid days drive air-conditioning load across the five boroughs just as the city's limited import capacity is most stretched, which is why summer reliability gets the most attention. Winter cold raises heating and gas demand, a growing concern as heating electrifies.
NYISO peaks on hot, humid summer afternoons, with New York City the most constrained zone. Cooling degree days are the number to watch here.
See live NYISO 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 NYISO region page.