More than half of B.C. is under a hot spell that will continue until Wednesday, partly due to hot air from the southwestern United States drifting north under a ridge of high pressure.

Temperatures in the Lower Mainland are expected to approach or exceed 32 C inland, and temperatures in many areas of B.C.'s Interior are forecast to spike to 40 C Sunday.

Medical health officers across the province are issuing joint news releases, urging everyone in affected regions to take precautions against heat exhaustion.

Fraser Health and Vancouver Coastal Health says children, seniors and people with chronic health conditions are particularly vulnerable to the effects of prolonged or excessive heat exposure.

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What are two good tips for staying well in hot weather? Take it easy, and stay hydrated.

"There are a variety of mild to severe symptoms linked with heat-related illness, including thirst, dizziness, confusion, weakness, fainting, collapsing and even death," a joint statement released Saturday said.

Here are six tips from B.C.'s medical health officers on staying well in hot weather:

1. Stay hydrated

Don't wait until you are thirsty to drink more water; check with your doctor if there are limits on the amount of fluid you are allowed.

2. Keep cool

Don't rely on fans alone when the air around you is also hot. Use cool mists or showers, spend time in air-conditioned rooms and buildings if you can, or make a visit to a pool or public water park.

3. Dress smart

Wear loose, light-weight clothing and shade yourself with a wide-brimmed hat and sunglasses. Stay in the shade or use sunscreen to avoid sunburn.

4. Get everyone out of the car

Children and pets should never be left alone in a parked car: Temperatures can rise to 52 C within 20 minutes in a vehicle when the outside temperature is 34 C, and leaving the windows cracked open won't make enough of a difference to make it safe.

5. Look out for each other

Check on your neighbours who are older, who live alone or who have difficulty leaving their homes, to make sure they are coping.

If you see anyone who isn't dealing with the heat, move them to a shady spot, get them hydrated, and call for help.

Someone who has a high body temperature and is either unconscious, confused or has stopped sweating may be suffering from heatstroke and  911 should be called immediately.

6. Stay informed

Read, watch or listen to local news and weather channels for updated weather statements and warnings, and call public services such as B.C.'s HealthLink BC at 8-1-1 for information on heat-related illness.

7. Just chill

If you have to do tiring work or exercise outdoors, try an get it done in the early morning or later in the evening. If you must exert yourself, drink two to four glasses of a non-alcoholic drink every hour.