BOISE, Idaho (AP) -- When the mercury hit 104, Rick Overton took his colleagues tubing on the Boise River, thinking it couldn't get much hotter.
A cyclist rides under water misters to keep cool in Palm Springs, California, on Thursday.
1 of 2 more photos » A day later, parts of the West were in for a little relief, but not everywhere -- Boise was expected to hit 107 degrees Friday.
"Once it gets that high -- 105, 107, 109 -- it just feels hot," said Overton, a copywriter for the digital marketing firm Wirestone.
Warnings of excessive heat were still posted Friday morning for much of Idaho, Nevada, Utah, Oregon and Washington state. The Southwest was expected to cool off slightly, though, said weather service meteorologist Jamie Meier.
"The high pressure system that has been stubbornly parked over Southern California is on a weakening trend, allowing temperatures to cool down to seasonable temperatures," Meier said.
For California firefighters who have been trying to put down a 1,500-acre wildfire in the rugged canyons above Santa Barbara, the cooler forecast could only sound good. Four had to be treated for heat exhaustion on Thursday.
"It's a matter of too much work and too much heat," said Santa Barbara County Fire Capt. Eli Iskow.
Temperatures climbed so high across much of the West on Thursday that authorities warned residents of southern Nevada, southeastern California and northwestern Arizona that outdoor activities could be dangerous except during the cooler early morning hours. Phoenix, Arizona, reached 115 degrees; Baker, California, reached 125 degrees.
At the Big Boy Restaurant in Baker, which has a 134-foot-tall thermometer outside, there was a run on cold shakes, general manager Enrique Munoz said.
"We had actually had to hire an extra shaker just to make shakes," he said.
Heat wave tips
• Drink lots of fluids, even when you?re not thirsty. If you are exercising in a hot environment, drink two to four glasses (16 to 32 ounces) of cool fluids every hour. But pass on the alcohol and sugary refreshments, as these make you lose body fluids.
• You lose important salt and minerals during heavy sweating, which should be restored. Drinks such as sports beverages can replace your salt and minerals.
• At home, wear as little clothing as possible and generally opt for lightweight, light-colored, loose-fitting attire. Protect yourself from the sun with a wide-brimmed hat, sunglasses and a sunscreen of SPF 15 or higher 30 minutes before going out. Reapply that sunscreen as directed.
• Limit outdoor activity to the morning and evening hours if you must be outdoors. Stay in an air-conditioned place if possible.
• Certain people are at high risk during heat waves, such children up to 4 years of age and adults 65 or older. Monitor those who are at risk. Children should not be left in cars unattended.
• Use common sense.
Source: Centers for Disease Control and Prevention
Even Stanley, Idaho, which at more than 6,000 feet elevation is routinely the coldest place in the lower 48 states, was seeing record highs, the National Weather Service said. The remote town in the Sawtooth Mountains reached 92 degrees Thursday, and was expected to hit 93 degrees Friday.
Hardly anyone in the tiny town has air conditioning, said Nancy Anderson, Stanley deputy city clerk. "They're all going to the lakes and the rivers and trying to find the shade," she said.
Summer temperatures across Utah are running 10 to 15 degrees above normal, meteorologist Brandon Smith said.
"To be honest, as far as temperatures, for as far out as we can see there's no relief," he said.
Around Las Vegas, Nevada -- where temperatures reached 116 degrees Thursday afternoon -- transformers overheated and caused electrical pole fires because of all the people switching on their air conditioners, said Scott Allison with the Clark County Fire Department.
Officials warned residents to take extra care. In Orfino, Idaho, a 1-year-old boy was found dead in a locked car in temperatures approaching 100 degrees on Wednesday. He was locked in the car for about five hours when passers-by noticed him, authorities said Thursday.
In Montana, farmers anxiously watched their crops and thermometers.
"Prolonged heat is devastating. Four or five days of it is going to be hard," said wheat farmer Lynn Nordwick near Poplar, Montana. Watch how a drought is spreading »
Northeastern Oregon residents experienced what was expected to be the hottest day of the year Thursday, with temperatures reaching 108 in Pendleton and 107 in Hermiston.
On Friday, Pendleton's forecast still called for triple-digit temperatures, and a red flag warning meaning a high danger of wildfires was posted.
The heat wave began last week after a large high-pressure center developed over Arizona, said National Weather Service forecaster Paul Flatt in Boise. A weather pattern was pushing that high-pressure center north into Canada, Flatt said, but most of the West is expected to experience high temperatures into next week.
Meanwhile, another round of heavy rain drenched parts of eastern Texas early Friday. State emergency management chief Jack Colley said all of Texas' major river basins are at flood stage, the first time that has happened since 1957
