Boise, Idaho ? Sweltering residents across the West headed for lakes and rivers on Thursday, seeking relief from triple-digit temperatures expected to set records through at least today.

Some office workers were given the option to float on innertubes down the Boise River instead of sitting at stuffy desks, with temps in Boise expected to reach 105 degrees. Forecasters predicted a high of 107 today – six degrees higher than the 101 record for that date set in 1985.

“Once it gets that high – 105, 107, 109 – it just feels hot,” said Rick Overton, a copywriter who arranged the float trip for the digital marketing firm Wirestone. “I’m going to keep a tube under my desk for the whole summer and whenever it gets this hot I’m going to escape.”

But temperatures in part of the West were climbing so high 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.

A 1-year-old boy was found dead Wednesday evening in a locked car in temperatures approaching 100 degrees in Orofino, Idaho. He was locked in the car for about five hours when passers-by noticed him, and the boy’s stepgrandmother was charged in his death, authorities said Thursday.

St. George, Utah, hit 111 by 1:30 p.m., a day after a nearby weather sensor recorded an unofficial reading of 118, which would top the the state’s all-time record of 117 set in St. George in 1985. 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.

Near Las Vegas – where temperatures reached 109 degrees before 1 p.m. Thursday – transformers were overheating and causing electrical pole fires because of all the people switching on their air conditioners, said Scott Allison with the Clark County Fire Department.