The National Weather Service has issued an extreme heat watch for the Grand Canyon effective Monday, with temperatures in the inner canyon forecast to reach 112 degrees Fahrenheit (44.4 Celsius). The warning, published Saturday, runs from 10 a.m. local time Monday through 7 p.m. Tuesday.
Forecasters at the NWS office in Flagstaff, Arizona, said “dangerously hot conditions” were possible below 4,000 feet, with daytime temperatures expected to range between 97°F (36.1°C) at Havasupai Gardens and 111°F (43.8°C) at Phantom Ranch.
“Most individuals will be at risk for heat-related illnesses without effective cooling or adequate hydration, especially with prolonged outdoor exposure,” the agency’s Flagstaff office said. The extreme heat watch is “reserved for only the hottest days of the year,” it added, and “issued when temperatures could rise to dangerous levels.”
The warning follows a series of recent heat-related deaths in the park. On Friday, the National Park Service said Grand Canyon rangers and emergency personnel responded to two separate incidents on June 12 and June 16 that resulted in three deaths.
“In both cases, the deceased hikers were hiking trails in the Inner Canyon, where temperatures can exceed 109°F in the shade during midday hours,” the NPS said.
According to park officials, on June 12 a 72-year-old man “succumbed to symptoms of heat-related illness” along the South Kaibab Trail. On June 16, in a separate incident, a 67-year-old man and a 68-year-old woman also appeared to have “succumbed to symptoms of heat-related illness” on the North Kaibab Trail, although the investigation remains ongoing.
“Despite rapid response and aerial support, all three individuals were found deceased when responders arrived,” the statement said.
Earlier this month, an 18-year-old man also died in the park after experiencing what authorities described as “heat-related symptoms.”
“Hiking in Grand Canyon can be a challenge for anyone, especially during the heat of summer,” the park service said Friday. “Recent increase in heat-related incidents comes as summer temperatures in the Inner Canyon have reached dangerous levels, creating conditions that can quickly overwhelm hikers during the hottest parts of the day.”
Weather officials urged hikers to avoid being in the canyon between 10 a.m. and 4 p.m. and advised against physical activity during those hours.
Elsewhere in Arizona, evacuation orders have been issued for communities between Sedona and Forest Highlands as firefighters work to contain the Pocket fire north of Sedona in the Oak Creek Canyon area.
Extreme heat watches have also been issued for parts of Oregon from Monday through Tuesday evening and for portions of California from Tuesday evening through Thursday, with forecasters warning of potentially dangerous temperatures. In Texas, the NWS office in San Angelo said “triple-digit heat” is expected from Sunday into early next week.
Heat advisories are currently in effect for parts of Alaska, Puerto Rico, Florida, and Texas, and are posted for Sunday in portions of Arkansas, Oklahoma, Texas, and New Mexico.
The heat comes as the U.S. is co-hosting the FIFA World Cup alongside Mexico and Canada. Earlier this week, a Guardian analysis found two matches of the tournament’s first round were played at a level of severe heat that a football players’ union has previously said should trigger the delay or postponement of games.