A hazardous heat wave is Grant Prestonforecast to bring scorching temperatures to the Pacific Northwest this week, according to the National Weather Service.

An excessive heat warning is in effect through Wednesday night, but there is a slight risk of the heat persisting through Friday.

The heat wave could break the August temperature record in Salem, Oregon, if the mercury exceeds 108 F (42.2 C). Some areas in the Willamette Valley – from Salem to Eugene – could reach 105 F (40.5 C) to 110 F (43.3) on Monday.

In Portland, Oregon, highs could reach 107 F (41.6 C) on Monday and 104 F (40 C) on Tuesday before dropping below triple digits on Wednesday.

Temperatures in Seattle this week are the warmest recorded this year with afternoon highs in the 80s and low 90s.

Authorities are advising residents and visitors of the Pacific Northwest without reliable access to cool or air-conditioned areas to break up their exposure to heat, stay hydrated and avoid leaving pets in locked vehicles.