It was nice while it lasted.
After weeks of relatively cooler than normal temperatures, Valley thermometers could spike on Sunday to 107, according to the National Weather Service website.
And by next week, the Valley may reach its first 110 of 2010.
Normal temperatures this time of year are 100 to 102. Wednesday's highs between 92 and 97 will stay below that under mostly sunny skies. Nighttime temperatures will be in the low 60s and 70s.
The heat-up starts Thursday, with a possible high of 100. Expect temperatures Friday and Saturday to reach 100 to 105, with 107 predicted for Sunday.
With the expected heat, the Valley of the Sun United Way is collecting bottled water to give out to the more than 8,000 homeless individuals living on Valley streets this summer. Donations can be dropped off at the United Food Bank in Mesa, 358 E. Javelina Ave.
It's also the time emergency rooms start to see adults and children with heat-related illnesses.
Emergency room physician Dr. Rustin Morse of Phoenix Children's Hospital, which has an urgent care location in Mesa, said early signs of heat-related illness include headaches, fatigue and tiredness. As the illness advances, victims may complain of muscle cramps, decreased sweating, excessive thirst and vomiting.
"This time of year we really, really worry about parents forgetting how hot cars can get and leaving their children in the car," Morse said. "It seems every year we have a fatality of a child in a car. Either a parent forgets or doesn't think about how hot it can get. It's really, really hot in those vehicles with the doors closed."
Morse said he sometimes sees infants in the emergency room who have been given too much water by well-meaning adults. Children 1 and younger shouldn't be given more than one 4-ounce bottle of water a day. They require more electrolytes and should be nursing or drinking formula, he said.
Other young patients Morse sees in the emergency room are those who are vomiting or have diarrhea from another condition. They're unable to keep down necessary fluids to cool their bodies and stay hydrated.
"Surprisingly, we don't see a lot of heat-related problems in the emergency department from children. I think it's because they can self-regulate. Most of the children are big enough that they'll drink when they're thirsty," Morse said.
According to the Arizona Department of Health Services, nearly 1,400 Arizonans suffer from serious enough heat-related illness symptoms each year to require a visit to the emergency room.
Last year, there were 110 deaths from exposure to natural excessive heat, according to a report released last month by the state. On average, 82 people died every year between 1992 to 2009 from heat stroke or sun stroke.