Groovee,
The Average max temp in August is around 29deg C, but this doesn't tell the whole story, it's not just the heat that's the issue it's the strength of the sun.
The canaries are nearer the equater than the UK or the Med resorts and so the sun's rays are much stronger (I assume because there's less atmosphere to go through).
If you're not accustomed to that type of heat and sun (and even if you ARE) you need to take great care at all times. In August you can burn in just a few minutes, you need to have strong factor suncream on at all times and the smart advice is to avoid the sun between noon and 3. This is especially important for children and fair skinned people.
It's all obvious stuff I know but you still see so many people walking around with horrendous sunburn.
Ole

Even now, in October, the sun is very strong. I was pleased to see so many children on the beach with those all in one sunsuits on (sorry not sure what they're called) that stop the suns rays from getting to their skin.

Thank you for the advice about the sun. Went to Florida this year and although I had factor 40 on in Seaworld and had topped up every 2 hours and then had 20 minutes in a shaded area, I managed to get badly burnt. Even my dh was surprised considering how careful I usually am. My 2 love their all in ones and usually have proper t-shirts on too. We're used to Salou weather so wanted to check for Lanzarote. So excited and can't wait.