Toronto residents are being warned about high heat and humid conditions on Monday as a humidex advisory dragged into its second week.

The City of Toronto ended a two-day old heat alert Monday morning, during a momentary break from scorching heat wave, but the threat of imposing humidity still had Environment Canada voicing concerns.

Environment Canada says residents in southwestern Ontario should expect hot, sticky conditions to continue Monday, after soaring temperatures reached record-breaking levels over the weekend.

Torontonians can expect a daytime high of 30 degrees Celsius and humidex values between 39 and 42, according to the weather office.

The city was getting some light showers Monday morning, with a risk of thunderstorms later in the day. Sporadic showers were anticipated through the afternoon and evening, with a low of 20 C overnight.

The forecast suggested that southern Ontario would get a slight reprieve from the humidity on Tuesday, with humidex values dropping to the mid-30s across most of the region. But the heat wave is expected to return mid-week and last into next weekend, with temperatures peaking in the mid- to upper-30s.

The scorching heat reached record temperatures over the weekend. Sunday's daytime high reached 34.6 C. The previous highest temperature for July 16 was set in 2002 at 34.4 C.

Residents of Toronto, as well as areas around Windsor, Hamilton and London, are being warned to keep hydrated and stay indoors as temperatures soar this week.

It is suggested that residents call or visit family, friends and neighbours who might be at risk of heat-related illnesses.

Isolated adults, seniors and those with medical conditions are at the greatest risk of becoming ill.

The City of Toronto recommended over the weekend that residents without air conditioning in their homes visit an air conditioned public place, including a shopping mall, library or community centre.

To avoid a heat related illness, the city suggests residents:
  • drink plenty of water, avoiding drinks which dehydrate the body including alcoholic beverages, coffee and pop
  • stay in the shade if going outside can't be avoided
  • avoid intense or moderate physical activity
  • keep blinds closed and curtains drawn over windows at home, with windows slightly open

Symptoms of heat illness can include difficulty breathing, weakness and dizziness, headaches and confusion. Anyone who feels faint or disoriented is advised to visit their doctor or the nearest hospital right away.