Heat wave grips London with warning issued for coming days

A multi-day heat wave continues to bake London, with daytime highs reaching into the mid-30s and feeling even hotter with the humidity.

Environment Canada has issued a heat warning for the region, with humidex values expected to reach between 37 and 42. Overnight lows will hover around 20 to 23 C, offering little relief.

"This heat event for London continues today. We expect a high temperature of 33 degrees, and that should continue tomorrow," said Shem Willie, a meteorologist with Environment and Climate Change Canada. "We have a ridge of high pressure over southern Ontario with southwesterly winds, bringing hot and humid conditions."

The hot, stagnant air is also expected to push air quality into the poor category, particularly in the afternoons.

The weather agency warns that extreme heat can pose serious health risks, especially for older adults, young children, people with pre-existing medical conditions and those who work outdoors.

Early signs of heat exhaustion can include headache, nausea, dizziness, thirst, dark urine and intense fatigue. Heat stroke is a medical emergency, with symptoms such as confusion, red and hot skin, and loss of consciousness.

Officials recommend:

• Drinking water regularly, before feeling thirsty.
• Limiting outdoor activity to cooler parts of the day.
• Wearing lightweight, light-coloured clothing and a wide-brimmed hat.
• Keeping living spaces cool or seeking relief in public air-conditioned spaces.
• Checking on vulnerable people in person or by phone.

The extreme heat is expected to break on Tuesday night when a cooler system moves through. However, Willie said there are early signs another round of high heat could return by next weekend.

It will be mainly cloudy on Tuesday with a 40 per cent chance of showers in the afternoon and a risk of a thunderstorm. Light winds and a high of 32 C, feeling more like 39 with the humidex. A mix of sun and cloud on Wednesday with a 40 per cent chance of showers and a high of 30 C. Thursday will be sunny with a high of 28.