Expect temperatures around the 20 degrees C mark at that time of year. We were in the south of Spain from 7th-14th April last year and the weather was great. One day was only 14 degrees with a cool North wind, but the rest of the time the temperatures were in the low to mid 20's. The only thing is that at that time of year sunny weather is not definitely guaranteed and it can be a little chilly in the evenings.

We went to Torremolinos(not sure where this is in relation to where you are going) in April (10th -24th) this year,the weather was lovely-low 70s the whole 2 weeks,certainly warm enough for shorts and t-shirts.The pools however were freezing,we had a small indoor pool at the hotel so this wasnot a problem.