Phoenix is experiencing a record-breaking warm December that is surpassing last year's high temperatures. The National Weather Service has confirmed through data collected at Sky Harbor International Airport, with an average temperature this month just above 63 degrees, making it the hottest December since records began in 1896. As Phoenix New Times reports, a persistent high-pressure system is partly to blame, which has led to fewer storms and higher temperatures.
Randy Cerveny, a professor of geographical sciences at ASU, shed light on the situation in an interview with KJZZ, explaining that while La Niña conditions—a cooling of the central Pacific Ocean—are partly responsible, "the underlying climate change" contributes to this extreme warmth. This effect is so profound that KJZZ notes the Climate Central's Climate Shift Index classified these temperatures as "extreme", indicating human-caused climate change makes such heat four times more likely.
Normally known for more temperate winter weather, Phoenix has seen daily highs that defy its usual cooler holiday norms. Mark O’Malley, a meteorologist with NWS Phoenix, points out that the region has only experienced a brief respite over Christmas with a "temporary blip" of cooler temperatures. However, the overall trend continues to hover above average, O'Malley told Phoenix New Times.
The implications stretch far beyond uncomfortable heat during what should be winter months. The lack of snow accumulation in Arizona's mountains threatens water resources, as O'Malley explained. Winter snow typically replenishes reservoirs, and with the current trajectory, this is a concerning development for Arizona's future water supply. The state especially relies on snow from the Mogollon Rim, a critical water resource, which O'Malley noted is seeing "a general lack of snow accumulation so far this winter," as per data from Phoenix New Times. Looking forward, while there may be a forecast for some "unsettled weather" that could bring storms and cooler temperatures, the overall outlook remains warmer than normal.
