PORTLAND, Ore. -- Temperatures Tuesday climbed into the upper 90s and forecasters expected another hot day Wednesday.

A high pressure system was expected to keep temperatures high through Thursday, according to Meteorologist Dave Salesky. After a short break, things were expected to heat back up again on Sunday.

"Central and Eastern Oregon will also have to keep and eye open for the chance of thunderstorms Tuesday. Then, the weather will cool down as we get to the later part of the week," Salesky said.

"The only spot to see a break from the hot weather will be the beach. Temperatures on the coast will reach the 60s and lower 70s," he added.

The National Weather Service issued a heat advisory for most of Oregon, including the Willamette Valley, the Hood River Valley and the Cascade foothills.

The advisory was expected to stay in place until Thursday afternoon.

Overnight temperatures will likely cool only into the 60s.

Authorities advise drinking plenty of fluids, staying out of the sun and checking on relatives and neighbors