Ypsilanti resident Luke Stolarski floats on his back after jumping from a bridge above the Huron River near Barton Nature Area Tuesday afternoon. Temperatures are expected to be in the mid-90s through Wednesday.

Jeffrey Smith | AnnArbor.com

Editor's note: This story, originally published Tuesday, was updated at 5:30 p.m. Wednesday with corrected information from county officials about when the cooling centers open.

People can seek the air-conditioned interiors of public libraries and malls as relief from the summer heat as 90-degree temperatures have sweltered the area Tuesday and Wednesday.

However, the weather isn't hot enough yet for county agencies to put its "Heatwave Response Plan" into action -- which would involve free transportation for the most vulnerable to designated cooling centers.

The heat isn’t entirely welcome - according to an AnnArbor.com poll, about 66 percent of respondents said they hated the weather Tuesday.

Wednesday’s weather continued into the lower 90 degrees. Thursday, temperatures are expected to reach a high of about 88 degrees, with a 50 percent chance of thunderstorms.

Friday, temperatures should reach a high of about 80 degrees, according to the National Weather Service.

A partnership of Washtenaw County agencies determines when the county's "Heatwave Response Plan" goes into effect. Partners include the American Red Cross Washtenaw County Chapter, City of Ann Arbor Office of Emergency Management, Ann Arbor Transportation Authority, Humane Society of Huron Valley, Washtenaw County Public Health Department and Washtenaw County Sheriff Emergency Services Division.

There are two thresholds officials use to determine when conditions are extreme enough to warrant implementation of the plan, said Marc Breckenridge, emergency services director of the Washtenaw County Sheriff's Office.

• After two consecutive days of heat advisories issued by the National Weather Service
• Very hot conditions combined with widespread power outages

During the plan, free transportation to designated cooling centers will be offered to the elderly, people with heat-sensitive conditions and people with disabilities by calling the County Emergency Operations Center at (734) 973-4900.

The centers are free and will be open to the public during business hours, when the county issues the order to put the plan into effect.

For now, here's a list of area public libraries where people can relax in air conditioning:

• Ann Arbor District Library at 343 S. Fifth Ave. in Ann Arbor
• Ann Arbor District Library, Pittsfield Branch, at 2359 Oak Valley Drive in Ann Arbor
• Ann Arbor District Library, Malletts Creek Branch, 3090 E. Eisenhower Parkway in Ann Arbor
• Ann Arbor District Library, West Branch, 2503 Jackson Ave. in Ann Arbor
• Ann Arbor District Library, Traverwood Branch, 3333 Traverwood Drive in Ann Arbor
• Chelsea District Library, 221 S. Main St. in Chelsea
• Milan Public Library, 151 Wabash St. in Milan
• Dexter District Library, 3255 Alpine St. in Dexter
• Saline District Library, 555 N. Maple Rd. in Saline
• Manchester District Library, 912 City Rd. in Manchester
• Ypsilanti District Library, Whittaker Branch, 5577 Whittaker Road in Ypsilanti
• Ypsilanti District Library, Michigan Branch, 229 W. Michigan Avenue in Ypsilanti
• Ypsilanti District Library, Superior Branch, 8795 MacArthur Boulevard in Ypsilanti

Amy Biolchini covers Washtenaw County, health and environmental issues for AnnArbor.com. Reach her at (734) 623-2552, amybiolchini@annarbor.com or on Twitter.