Weather is one of the most often asked questions we see on the message boards. It's also one of the most difficult to predict, particularly during transition periods... that are basically between seasons.
All I can tell you is that when we did an April transatlantic crossing, we had temps in the 70s almost every day, and seas as smooth as a bath tub. Hopefully you'll be as lucky!!
Kar... I will be on that TA with you. I went to a weather website and put in the port cities to get average temps for April. Average seems to be in the mid-60's during the day, cooler at night. That's sweater and long pants weather for me. I'm also packing a light jacket/rain coat and a small compact umbrella. I plan on dressing in layers. It's always cooler on the water, too, so I don't have high hopes of much pool time.