Hi Michele,
We were in Corfu for our silver wedding Anniversary 2 years ago 5th-12th May. We were pleasantly surprised with the weather. However, when we woke up the first morning it was bucketing down with rain which did slacken as the morning went on. By about
2pm we were sunbathing around the pool. From then on it was dry all week with temps averaging about 21c. We both had brilliant tans. As it was the first week of the season the swimming pool hadn't had time to warm up but nevertheless I gritted my teeth and went for it (every day). A scotsman and myself were the only ones brave enough to enter the pool every day. I think my husband did take a 5 minute dip one day. The sea was too cold even for me.
The evenings were obviously much cooler and I needed a cardigan or light jacket. I'd also pack some jeans just in case. Have fun in Paleo. We visited on a day trip about 15 years ago and it was beautiful. It was a very quiet and laid back resort at the time. No doubt it must have developed somewhat since then.