Phoenix is hot and dry, with extreme summers regularly above 110 degrees Fahrenheit and mild winters. Cooling, not heating, defines the grid here. Below: live conditions, the 7-day outlook, and what it means for electricity demand on the Desert Southwest (WECC) grid.
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High and low temperatures, with the implied heating and cooling demand below.
Phoenix is one of the fastest-growing data-center markets in the US, on cheap land, abundant solar and a pro-build posture. Demand is overwhelmingly a summer cooling story: brutal heat drives air-conditioning load for months, and solar output, while huge, fades right as the evening cooling peak holds. The desert grid leans hard on gas and, increasingly, batteries to cover that ramp.
The Desert Southwest peaks on hot summer late afternoons and early evenings, when cooling load stays high but solar is dropping off.
See live Desert Southwest (WECC) 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 Desert Southwest (WECC) region page.