On Monday, the National Weather Service issued an excessive-heat warning for southern Utah's Dixie and Lake Powell area — which includes St. George, Zion National Park, Glen Canyon National Recreation Area and Bullfrog — that likely will remain in effect until 10 p.m. Thursday.
The warning means that a prolonged period of "dangerously hot" temperatures will occur. The weather service warns that exposure to the heat could lead to dehydration, hyperthermia, heat cramps, heat exhaustion or heat stroke.
Recommended precautions include avoiding strenuous outdoor activities during the heat of the day, drinking plenty of fluids and staying out of the sun and in an air-conditioned room. People are urged to check on relatives and neighbors.
For those who work outdoors, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location, OSHA says.
"Heat stroke is an emergency — call 911," the weather service says in its warning.
Also on Monday, a heat advisory was issued for the lower elevations of the San Rafael Swell and south central Utah. An advisory, this one set to be in effect until 10 p.m. Thursday, is issued when a period of hot temperatures is expected; the predicted highs in these areas are a few degrees cooler than in southern Utah.
The San Rafael Swell, including Green River and Hanksville, is predicted to have highs on Tuesday and Wednesday of about 106 and 108, respectively. Those temperatures would break Green River's record high of 103 for June 20 (set in 1968) and June 21 (set in 2005).
The rest of the week will remain hot for the San Rafael Swell, with temperatures topping out at 106 on Thursday and 104 on Friday, and in the upper 90s on Saturday and Sunday, the weather service says.
In south central Utah, including Grand Staircase Escalante National Monument and Kanab, the weather service is predicting highs of 103 on Tuesday and 104 on Wednesday. Highs ranging from the upper 90s to 102 are predicted in the area for the rest of the week.
Editor's note: This story has been updated throughout the day.