Last year when we came out in July (2nd/3rd week) it was probably hotter in the uk (south west?) than it was in Calis. I remember it being mid 30's in Calis.
The previous year at the same time it hit 50 degrees in direct sun - very hot, but a dry heat which is manageable if you use the pool/sea to cool off. Not like Dubai, which we went to at totally wrong time of year (summer), temp was 50 degrees but so humid it was bloody uncomftable - you were drenched within a few moments of going outside.
Use all the relevant sun creams, keep out of the sun at midday and you will have a great time.