Torontonians are bracing for what promises to be a scorching hot week in the city. A heat warning, yellow alert, has been issued for Toronto and much of southern Ontario this week as humidex values approach 45. Environment Canada is calling for a high of 33 C on Monday, feeling closer to 38 with the humidity. “Over the next few days, there really is no relief,” CP24 Weather Specialist Jess Smith said Monday. “It is hard when you have to work outside, you have kids in camps.” She noted that Tuesday could be a “record-breaking day” when it comes to the heat. “It is going to challenging to spend any time outside,” she said. On Tuesday, which is expected to be the “peak” of the heat event, the mercury will rise to 37 C, feeling closer to 45. “Hot and humid air can also bring deteriorating air quality and can result in the Air Quality Health Index approaching the high-risk category,” the weather advisory from Environment Canada read. “Take action to protect yourself and others – extreme heat can affect everyone’s health. Determine if you or others around you are at greater risk of heat illness. Check on older adults, those living alone and other at-risk people in-person or on the phone multiple times a day." Wednesday will see a daytime high of 33 C with a chance of showers. The temperature will dip down to 31 C on Thursday and 28 C on Friday. “Watch for the early signs of heat exhaustion in yourself and others. Signs may include headache, nausea, dizziness, thirst, dark urine and intense fatigue. Stop your activity and drink water,” the national weather agency wrote. “Drink water often and before you feel thirsty to replace fluids.” Heat stroke ‘a medical emergency’ Speaking to CP24 on Monday, Dr. Allan Grill, Chief of Family Medicine at Markham Stouffville Hospital, outlined the stages and symptoms of heat-related illness. “If you aren’t keeping well-hydrated... the first thing that happens is get these heat cramps,” he said. “You get a lot of muscle cramps all over the body, you feel really achy.” He noted that without intervention, it will progress to what is known as “heat exhaustion.” “What happens is people get weak and dizzy because their blood pressure drops, they tend to get headaches and sometimes they can even start to vomit and that unfortunately makes you even more dehydrated,” Grill noted. “If you start to see those signs or symptoms, get that person into a cool place, use some cold compresses like a cold washcloth on their skin, give them something to drink.” He noted that if the illness advances even further, it becomes a medical emergency. “Unfortunately, if you ignore the first two, you can end up with something called heat stroke. Heat stroke is when the body temperature goes above 40 degrees, your body loses its ability to sweat so you can’t cool off, people have a decreased level of consciousness,” he said, adding that a call to 911 is necessary at this stage. “Get them medical care immediately,” he said.