When I was in Palmiye, October 2005, the pool at the hotel was heated, and that was
very nice! (Very relaxing, at the end of the afternoon...

) The weather in early April
will, of course, be much better than in northern Europe, but it will not be real summer:
Shielded from the wind and in the sun it will be nice but the wind will make it chilly.
The evenings certainly will be chilly. In 2006, I was at Djerba Méridiana by the end
of April; there and then, the weather was sunny but windy, and generally, Djerba is
warmer than the Turkish south coast. Do expect some clouds and some rain, too. If
you go, bring at least a sweater.
"Do, or do not. There is no 'try'." (Yoda, The Empire Strikes Back)