Definitely sunbathing weather in the day!

Take lots of high factor suncream!
As for nightimes, we went at Easter (first two weeks in April) 2007, and it was quite chilly at night with a cold wind in the first week (everyone was wearing winter jackets for the outside entertainment), but the second week was a little warmer in the evenings, but still comfortable for sleeping without being all sticky. Haven't been at the end of April/beginning of May, but I have been to Tenerife at this time and it was a little chilly some evenings and a bit warmer on other evenings.
We are off to Fuerteventura again next Easter and plan to take a couple of thick cardies or nice spring jackets to wear in the evening, but lots of suncream for in the day.