Temperatures soaring to potentially deadly levels this week in the Sauk Valley

The National Weather Service issued a heat advisory for Sunday through at least Wednesday for most of northern Illinois, including Lee, Ogle, and Whiteside counties, although relief appears to be least a week away.

Temperatures are expected to reach the mid to high 90s through Friday, with humidity making it feel close to 110 degrees at times, the Weather Service said.

The danger

Being exposed to excessive heat can lead to sunburn, heat cramps, heat exhaustion and heat stroke and death.

It also can be deadly for animals left exposed to the sun and without adequate water.

Heat-related illnesses can creep up on a person, so it is important to know the signs. A complete list is at Extreme Heat | Ready.gov.

Here is some of what you should know:

Heat cramps

Those who are having heat cramps in the legs or abdomen should be taken to a cooler place, where they should rest, lightly stretch the affected muscle, and drink about 4 ounces of cool water every 15 minutes to replenish their fluids.

Heat exhaustion

Signs of heat exhaustion include cool, moist, pale or flushed skin, heavy sweating, headache, nausea, dizziness, weakness and exhaustion. Those experiencing such symptoms should be moved to a cooler place. Remove or loosen tight clothing, mist them with water or apply cool, wet cloths or towels to their skin.

If they are conscious, give them small amounts of cool water to drink, and make sure they drink it slowly. Watch for changes in their condition. If they refuse water, vomit or begin to lose consciousness, call 911.

Heat stroke

Heat stroke usually occurs when the signs of heat exhaustion are ignored. It develops when the body systems are overwhelmed by heat and begin to stop functioning.

Signs include hot, red skin that may be dry or moist; changes in consciousness; vomiting and a high body temperature.

Call 911 immediately if someone shows signs of heat stroke. Move them to a cooler place, and quickly cool them by immersing them up to their necks in cold water if possible. Otherwise, douse or spray them with cold water, or cover them with cold, wet towels or bags of ice.

Risk factors

Heat is the leading weather-related killer in the U.S., according to the American Red Cross said, and more than 600 people die every year from heat-related illnesses, according to the Centers for Disease Control and Prevention .

Those more at risk of developing a heat-related illness include people older than 65, those with chronic medical conditions, people who work outside, infants and children, and athletes.

Some people may take medications that make the effects of extreme heat worse. People with heart disease, poor blood circulation, obesity and mental illness are also at risk for getting sick if the temperatures climb.

Take precautions

The Federal Emergency Management Agency has these tips:

• Limit your time outdoors and stay in an air-conditioned indoor location as much as you can. Go to a public place like the library, museum or shopping mall if you don’t have A/C at home. (A list of Sauk Valley cooling centers is available below.)

• Don’t rely on a fan as your primary cooling device. Fans create air flow and a false sense of comfort, but do not reduce body temperature or prevent heat-related illnesses.

• Roughly 40% of unwanted heat buildup in our homes is through windows, so use awnings, curtains or other window coverings to keep the heat out and check the weather stripping on doors and windows to keep the cool air in.

• Drink plenty of fluids even if you don’t feel thirsty.

• Wear loose, lightweight, light-colored clothing, along with a hat and sunscreen when outdoors.

• Take cool showers or baths to cool down.

• Check on friends and neighbors and have someone do the same for you. Older adults, people with chronic medical conditions and children are at greater risk from dangerously high temperatures.

• Never leave children or pets in cars.

• Check the local news for health and safety updates.

The forecast

Today: Sunny, with a high near 93. Heat index values as high as 105. Northeast wind 5 to 10 mph.

Tonight: Partly cloudy, with a low around 69. East wind 5 to 10 mph, with gusts as high as 20 mph.

Monday: Mostly sunny, with a high near 91. East wind around 10 mph.

Monday night: Partly cloudy, with a low around 67. East wind 5 to 10 mph.

Tuesday: Sunny and hot, with a high near 95.

Tuesday night: Mostly clear, with a low around 73.

Wednesday: Sunny and hot, with a high near 99.

Wednesday night: Mostly clear, with a low around 75.

Thursday: Sunny and hot, with a high near 99.

Thursday night: Partly cloudy, with a low around 73.

Friday: Mostly sunny, with a high near 91.

Friday night: Partly cloudy, with a low around 63.

Saturday: Mostly sunny, with a high near 80.

Cooling centers

Lee County

Parkhurst Memorial Library, 3 S. Jefferson Ave., Amboy. 1-7 p.m. Monday and Wednesday, 9 a.m. to 3 p.m. Tuesday and Thursday, 9 a.m. to 3 p.m. Friday and Saturday.

Mills and Petrie Memorial Library, 704 N. First St., Ashton. 1-6:30 p.m. Monday to Thursday, 10 a.m. to 1 p.m. Saturday.

Dixon Public Library, 221 S. Hennepin Ave., Dixon. 9 a.m. to 8 p.m. Monday to Wednesday, 9 a.m. to 5 p.m. Thursday and Friday, and 9 a.m. to 1 p.m. Saturday.

Lee County Senior Citizens Center, 110 W. Second St., Dixon. 8 a.m. to 5 p.m. Monday to Friday.

Franklin Grove Library, 112 S. Elm St., Franklin Grove. 10 a.m. to 8 p.m. Monday to Thursday, 10 a.m. to 2 p.m. Friday and Saturday.

Walmart, 1640 S. Galena Ave., Dixon, 6 a.m. to 11 p.m.

Whiteside County

Walmart, 4114 E. Lincolnway, Sterling, 6 a.m. to 11 p.m.

Walmart, 1901 First Ave., Rock Falls. 6 a.m. to 11 p.m.

Sterling Police Department, 212 Third Ave., Sterling. All hours.

Sterling Public Library, 102 W. Third St., Sterling. 9 a.m. to 8 p.m. Monday and Tuesday, 9 a.m. to 5 p.m. Wednesday to Friday, 9 a.m. to 1 p.m. Saturday.

Whiteside County Sheriff, 400 N. Cherry St., Morrison. All hours.

Odell Public Library, 307 S. Madison St., Morrison, 10 a.m. to 8 p.m. Wednesday, 2 p.m. to 8 p.m. Thursday and Friday.

Kickback Saloon, 102 N Main St., Tampico, 10 a.m. to noon.

Whiteside County Community Health Clinic, 1300 W. Second St, Rock Falls. 8 a.m. to 4:30 p.m., Monday and Friday, 7:30 a.m. to 6 p.m., Tuesday to Thursday.

Rock Falls Public Library, 1007 Seventh Ave., Rock Falls. 9 a.m. to 7 p.m., Monday to Thursday, 9 a.m. to 4 p.m. Friday, 9 a.m. to 1 p.m. Saturday.

Community Building, 603 W. 10th St., Rock Falls, 10 a.m. to 4 p.m.

Erie Fire Station, 807 Ninth Ave., Erie. 10 a.m. to 5 p.m. Call in advance.

Albany Fire Department, 409 N. Church St., Albany. All hours during a heat advisory.

IDHS: The public offices of the state’s 120 Illinois Department of Human Services also serve as cooling centers. That includes the Family Community Resource Center, 2605 Woodlawn Road, Sterling and the Family Community Resource Center, 1001 Pines Road, Oregon.