The hot air is at low altitude so it will affect coastal areas of Gran Canaria as well as the highlands. The only area that may escape the highest temperatures is the north coast where the trade winds will buffer the heat (but only a bit).
It comes with a brisk and warm wind and plenty of airborne dust on Thursday, Friday and probably the weekend. The forecast is for gusts of wind up to 70kmph in the highlands.
These classic summer Sirocco conditions with hot dry air and wind mean that south Gran Canaria is on yellow alert (34ºC+) on Thursday for heat. This rises to orange alert (37ºC+) on Friday. The rest of the island is on yellow alert on Friday. Expect the alert to continue until Sunday when it looks like the worst of the heat will start to fade.
Friday and Saturday will be the hottest days.
Gran Canaria is currently on maximum fire alert due to the weather. There's already a raging fire on La Palma island so the last thing we need is another one to divide resources.
Almost all forest fires in the Canary Islands are caused by people (accidentally or on purpose). We'd advise everyone to stay away from the Cumbres for the next few days as it is far too hot for walking and fires can start from a single spark (from a car hitting a rock, dropped cigarette, etc).
Anyone lighting a BBQ in Gran Canaria's mountains this weekend can expect to be arrested.
Follow standard precautions like drinking lots of water, staying out of the midday sun, applying plenty of sunscreen, and avoiding strenuous exercise.
As always, the best way to survive a Gran Canaria heatwave is to stay in water up to your neck and be within easy reach of cold beer.