Climate scientists are raising alarms that a powerful El Niño developing in the Pacific Ocean could make Arizona’s already severe summer conditions even worse, bringing hotter, drier stretches and compounding risks from flooding, wildfire and public-health threats. The phenomenon, described by panelists as potentially the largest El Niño on record, has researchers and emergency officials watching seasonal forecasts closely and preparing for the kinds of extremes the state has seen in recent years.
A thermometer registering high temperatures beneath a blazing sun — a visual for Arizona’s scorching heat that climate scientists warn could intensify with a 'Super El Niño.'
“It has been one of the biggest weather stories we have seen,” Shel Winkley, a meteorologist with Climate Central, told reporters at a briefing convened by a local climate action group. El Niño refers to warming of surface waters in the central and eastern tropical Pacific that alters atmospheric circulation and shifts weather patterns across the globe. A strong El Niño is typically linked to warmer, drier conditions across the northern United States and to heavier rainfall in parts of the Gulf Coast and Southeast, but the scale of impacts depends on how the event evolves.
Scientists on the panel said the current event is breaking records as it forms and has the potential to set off unprecedented weather extremes. Forecast models for Arizona this summer point toward generally drier and hotter conditions during the peak months, with some projections indicating the possibility of increased precipitation later in the season. Michael Crimmins, a climate science professor at the University of Arizona, said the outlooks offer “a little hope” for late-season rains but emphasized that his analysis of prior El Niño years suggests any uptick in monsoon-related precipitation is likely to be delayed until late August or early September.
Arizona’s recent climate history amplifies those concerns. The state has already moved noticeably toward hotter annual averages, with a 3.4 degree Fahrenheit increase in mean temperature since 1970, and that warming trend has coincided with a drop of roughly 2.7 inches in annual precipitation over the same period, Winkley and Climate Central data show. Record-setting heat last year followed a moderate El Niño in 2023; those temperature highs were exceeded in 2024, when Phoenix recorded a run of 113 consecutive days with maximum temperatures at or above 100 degrees — the longest such streak on record. By comparison, the previous longest runs were 76 days in 1993 and 66 days in 2023, and Phoenix’s maximum temperature was at or above 100 degrees for approximately 30% of the year in 2024.
The practical consequences of hotter, drier summers and erratic storms are already visible across the state. Last year, heavy flooding devastated the small mining community of Globe and killed four people; local officials have since pursued state funding to repair damage after the Federal Emergency Management Agency declined to provide assistance. Wildfires, too, have been growing in intensity amid drier conditions, and health officials warn that warmer, more arid weather is linked to increases in illnesses spread by insects such as mosquitoes and ticks, as well as respiratory and fungal diseases that thrive in dusty, disturbed soils.
Juan Declet‑Barreto of the Union of Concerned Scientists called the approaching months a potential “triple danger season,” saying that extreme weather, strains on federal forecasting and disaster-response systems, and affordability pressures for housing and energy combine to elevate risk for many Arizonans. “We are seeing a compromised (National Oceanic and Atmospheric Administration) that is still reeling from staffing cuts and shortages,” he told reporters, adding that FEMA and other federal disaster-related agencies have faced deep budget reductions under the current administration. The panel noted that NOAA plays a central role in forecasting large storms and other climate-related hazards; reporting has indicated the administration has proposed significant cuts to parts of the agency ahead of the hurricane season.
Public-health specialists and infectious disease researchers at the briefing highlighted several ways that a warming climate is already reshaping disease risks. Vector-borne illnesses transmitted by mosquitoes, ticks and fleas have expanded their ranges and seasons as temperatures rise, contributing to increases in cases of West Nile virus, Lyme disease and, in some regions, malaria. In the Southwest, increased heat, prolonged dry spells and construction disturbance in desert soils are associated with a rise in coccidioidomycosis, commonly known as Valley fever, which results from inhaling fungal spores that flourish under such conditions.
Water scarcity and wildfire risk remain central concerns if the El Niño evolves into a very strong event. Drier conditions over many months reduce soil moisture and reservoir inflows, stressing municipal and agricultural supplies; surface-water levels already display year-to-year variability that leaves some storage systems with visibly low margins. At the same time, prolonged dryness and higher temperatures increase the number of days each year when fire risk is elevated. Winkley said those drier conditions have already added between 40 and 60 extra days per year to Arizona’s wildfire season, a change that can make individual fires more difficult to control and expand the window for destructive blazes.
A desert dam and reservoir with a visible low waterline, illustrating water stress in Arizona that could be exacerbated by shifts in precipitation linked to a 'Super El Niño.'
Researchers said emergency managers and public-health officials are watching model guidance and seasonal outlooks carefully, and they urged preparedness measures appropriate for heat, wildfire and flood threats as forecasts become clearer. While some models leave open the possibility of increased late-season precipitation, the near-term picture for much of the summer points to conditions that could intensify the heat and dryness Arizonans have experienced in recent years. The scientists concluded by stressing the need to monitor developments as the season advances and to plan responses based on evolving forecasts and local vulnerabilities.