Temperatures are expected to remain high again Wednesday, before returning closer to normal on Thursday.

Capital Weather Gang reports the District had gone nearly eight years without reaching 100 until June 22, when it again touched the century mark. The recent heat wave has prompted local governments to take action.

D.C. Public Schools, which hosts several academic programs and camps during the summer months, canceled outdoor activities due to extreme temperatures, a district spokeswoman said. Surrounding school districts — including those in Arlington and Fairfax County — also moved to cancel outdoor programs, such as recess and team practices.

Mayor Muriel E. Bowser (D) on Saturday activated an Extended Heat Emergency through Wednesday, opening cooling centers and homeless shelters around-the-clock.

Despite health warnings, urgent care centers affiliated with Inova have seen an uptick in heat-related illnesses this month and have sent several people to emergency rooms for IV fluids and testing, said Meredith Porter, the medical director for the 22 GoHealth locations in Northern Virginia.

Mild heat-related illness can begin with swelling in extremities and muscle cramping and progress to heat exhaustion with dizziness, headache and fatigue, both of which can be treated at most urgent cares. But heat stroke, with neurological symptoms, such as confusion and agitation, requires rehydration at an emergency department.

Porter stressed that anyone, regardless of age and health status, can be sidelined by the high heat and humidity our region and East Coast are experiencing.

“Most of these heat-related illnesses are largely preventable,” Porter said. “Anybody can be affected by a heat-related illness so having that awareness is the most important part of this.”

Anyone who works outside, such as athletes, construction workers, firefighters and medics as well as members of the military, should take extra precautions, she said.

High risk groups include people who are under 15 and above 65, pregnant, have chronic medical conditions like heart and lung disease and diabetes, are taking certain medications and have experienced heat exhaustion or heat stroke in the past, Porter said.

People experiencing homelessness or anyone lacking access to shade, air conditioning or water also need extra attention at this time, she said.

She urged residents to check on elderly neighbors and make sure to stay hydrated with water, not caffeine or alcohol, wear light loose clothing and a hat, use sunscreen and even an umbrella. It’s never safe to leave children or pets alone in a car, but that’s critical in a heat wave, she said.

Monday was so hot that piece of the Blue and Yellow Line metal track near National Airport bent sideways, causing what is known as a “heat kink.”

Metro spokeswoman Whitney Nichels says the bent rail was fixed overnight and the rail was fully functional as of Tuesday.

Any time outside temperatures rise above 90 degrees, Metro workers check the rail lines for kinks, which can happen when the heat has made the metal expand beyond its cross ties. If the rails are 135 degrees or hotter, trains have to slow down on outside track to 35 miles an hour to avoid a catastrophe caused by deformities in the rail line.

The extreme temperatures made Carla Brewster think twice Tuesday afternoon when she walked across Montello Street in Northeast Washington and found a man unable to respond.

Brewster, 40, of Trinidad, cautiously jostled him and tried to give him food and water, but ultimately called 911.

Paramedics, unsure whether drugs, alcohol, the high temperatures or some combination of factors were to blame, moved him to a cool ambulance where they tucked ice packs around him and rushed him to a hospital.

“His head was under the tree, his body was hanging out in the street, if somebody decided to park they probably would have run over him,” she said. “I know it’s hot out here.”

Ian Livingston, Jason Samenow and Rachel Weiner contributed to this report.