PORTLAND, Ore. (KOIN) -- Multnomah County's cooling centers have expanded the days they're open as the prolonged heat wave hitting the region continues on Monday and as county officials announce three suspected heat-related deaths.

Triple digits are still in the forecast for much of the Portland and Vancouver metro areas on Monday and Tuesday, and an excessive heat warning issued by the National Weather Service has been in effect for the region since July 4.

The cooling centers, which were initially slated to close Sunday evening, reopened again on Monday, July 8 from noon to 10 p.m. and will be open again on Tuesday, July 9 at noon, according to county officials.

The Multnomah County cooling centers are at the following locations:

• Cook Plaza, 19421 SE Stark St. Gresham
• Portland Covenant Church, 4046 NE Martin Luther King Jr. Blvd, Portland
• Congregation Beth Israel, 1972 NW Flanders St, Portland

These cooling centers allow pets and will provide snacks and water to those in need.

Meanwhile, Multnomah County's central library in Downtown Portland and the Gresham Library on NW Miller Avenue will extend their hours until 9 p.m. on Monday.

On Monday, Multnomah County officials announced three suspected heat-related deaths of residents, with one on Friday, July 5 and two on Sunday, July 7. A fourth suspected heat-related death happened when a non-Multnomah County resident was taken to a Portland area hospital and died from a suspected heat-related illness, according to officials; it's unclear where the person was from at this time.

In Washington County, Beaverton's main library will have extended lobby hours from 7 a.m. to 9 p.m. on Monday, July 8 and Tuesday, July 9. Twenty-four-hour cooling shelters are also at the Washington Street Conference Center and Beaverton Community Center, according to Washington County officials.

In Clackamas County, Father's Heart Street Ministry in Oregon City will remain open for overnight cooling until Tuesday, July 9 at 8 p.m.; the county's full list of daytime cooling centers can be found here.

The National Weather Service's excessive heat warning is slated to expire on Tuesday night, but temperatures aren't forecasted to cool down beyond the upper 80s for the rest of the week.