Environment Canada has issued a heat warning for the Comox Valley and Campbell River regions of eastern Vancouver Island.

A strong ridge of high pressure is building over the region that will cause daytime highs to reach the high twenties. Overnight lows are expected to be in the high teens.

The above average heat is expected to persist until the end of the weekend at which time the ridge will break down and temperatures will cool, Environment Canada says.

Environment Canada and local Medical Health Officers expect an increase in health and safety risks from heat and are advising the public to take precautions.

Heat affects everyone, but the risks are greater for: seniors, people who live alone, people with pre-existing health conditions such as diabetes, heart disease or respiratory disease, people with mental illness such as schizophrenia, depression, or anxiety, people with substance use disorders, people with limited mobility.

The public is urged to check on family, friends and neighbours who are at higher risk, particularly if they live alone, to make sure they have a cool space. Watch for the effects of heat illness: heavy sweating, rash, cramps, fainting, high body temperature and the worsening of some health conditions. Keep your house cool. Turn on your air conditioning (if possible), block the sun by closing curtains or blinds, or relocate to a cooler location such as a basement or public cooling centre.

Fans alone cannot effectively lower core body temperature, especially for older adults. Use fans to pull in cooler air from outdoors, but if you or someone you care for is experiencing symptoms of heat illness, find a cooler space.

Watch for early signs of heat illness (feeling unwell, fatigue, thirst, headache, unusually dark urine) as these can rapidly evolve into life-threatening emergencies. Move to a cooler environment immediately, such as a shaded or air-conditioned space. Drink plenty of water regularly, even before you feel thirsty to decrease your risk of dehydration. Thirst is not a good indicator of dehydration.

Watch for early signs of heat illness (feeling unwell, fatigue, thirst, headache, unusually dark urine) as these can rapidly evolve into life-threatening emergencies. Ask a health professional, such as a pharmacist or physician, how medications or health conditions can affect your risk in the heat.

Anyone working in the heat should take regularly scheduled breaks in a cool or shaded space. Never leave susceptible people, particularly children, or pets inside a parked vehicle. If you are in an overheated area, seek a cool place such as a tree-shaded area, splash pad, misting station, or air-conditioned spot like a public building.

To get more information: Check the local news for health and safety updates. Check HealthLinkBC online resources about heat-related illness and how to protect yourself at . Call HealthLinkBC at 8-1-1 to ask about heat-related illness.

Continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to BCstorm@ec.gc.ca or tweet reports using .