Hey, last year I visited Hvar in April and it was great weather for exploring, while walking or being in the sun it felt hot but I tried the sea several times and its cold. The sea becomes nice around mid of May tbh.

You can expect around 15c+, feeling much hotter in sun, but in the evening you need layering as it still is chilly around 10-11c. 

Heres a great guide for Croatia in April: CROATIA in April: Guide to visiting Croatia in Spring

Weather in April on Hvar you can expect great weather for exploring if you get sunny period, the rains and cloudy days are less frequent compared to March, we were doing week and half and got all sunny beautiful days, in the previous year for the same time we got mostly cloudy days, not really raining so it really depends. If you can decide a week before would be best to grab nice weather.

Hvar Day Trip Itinerary: Best Things to see and do on Hvar

Beaches on Hvar Island: Best Beaches Close to Hvar Town

It is not warm enough to swim in April but there are locals that go swimming in February so it really depends on your tolerance to cold water. 

Honestly there is no point in going beach hopping in April on Hvar unless you want to see the beaches but you wont be able to enjoy them that you can from June when the sea is much warmer. 

We going in April, will share our experience! thanks for great information