COEUR d'ALENE -- North Idaho and much of the Inland Northwest are under a heat advisory until 8 tonight, with temperatures expected to reach the upper 90s.
"There's a ridge of high pressure that's parked over the Pacific Northwest," said Valerie Thaler, a meteorologist with the National Weather Service Forecast Office in Spokane.
Ridges of high pressure bring with them clear skies and air that compresses and heats up as it sinks.
"Under those conditions, it really allows the sun to heat up the ground," Thaler said.
Things are expected to cool down Thursday, with temperatures in the 70s later in the week and this weekend.
Officials said the high temperatures spell a major heat risk in the Coeur d'Alene area. In such hot conditions, anyone without adequate cooling and hydration is at increased risk of heat-related illness, not only vulnerable populations such as children and elderly people.
To combat heat exhaustion, drink lots of fluids and avoid alcohol and caffeine. Take breaks when working outside.
High temperatures pose a risk to animals, too. Pet owners should take care when exercising their pets and avoid going out during the hottest parts of the day, according to the Humane Society of the United States.
"People should consider canceling any outdoor plans they have, moving into air-conditioned spaces if possible and staying hydrated," Thaler said.