A heat warning and a special air quality statement has been issued for Waterloo region, Guelph and surrounding areas.

Environment Canada says winds have carried smoke from northern Ontario, causing poor air quality in local areas.

"As smoke levels increase, health risks increase. Limit time outdoors," the statement says. "Consider reducing or rescheduling outdoor sports, activities and events."

The statement warns of common symptoms. It can range from milder symptoms like eye, nose and throat irritation to wheezing, chest pains and severe cough.

"When indoors, keep windows and doors closed as much as possible. When there is an extreme heat event occurring with poor air quality, prioritize keeping cool," the statement says. Environment Canada recommends using a clean air filter to help remove fine particles from the air.

There's also a heat warning in effect for southern Ontario. The weather agency says there will be hot, humid weather through to Thursday night.

On Monday, the temperature is expected to reach 31 C, but feel like 39 C with humidity. 

On Tuesday, the high is expected to be 32 C with a humidex of 35 C.

"Extreme heat can affect everyone's health," the warning says.

"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."

The warning says early signs of heat exhaustion can include headaches, nausea, dizziness, thirst, dark urine and intense fatigue. It is urging people to drink water and close their blinds.

Steven Flisfeder, a meteorologist for Environment Canada, is reminding people to stay hydrated.

"General recommendations ... like drinking lots of water, especially before you start to feel thirsty, just so you're continuously hydrated through the heat. Limiting time outdoors, especially strenuous activity, as well as especially during the hottest parts of the day, which is typically in the late afternoon, early evening time frame," he said.

"Make sure you have a cool shaded area where you can find relief during those hottest parts of the day."

Environment Canada is predicting highs of over 30 degrees on Monday and Tuesday, with a 40 per cent chance of showers on Wednesday and a 60 per cent chance of showers on Thursday. 

The rainy, cloudy weather is also expected to carry through the weekend.