Thailand in april(getting a tan)?

i'm going to thailand in a couple of weeks, i've heard it should be really hot and being a beach bum am happy about this, however recent weather reports have shown thunderstorms over the last week and look to continue. i'm going for 3 weeks, is there a chance i won't come home tanned? also what is thailand like in april, ive read mixed reviews. i will be going to bangkok, phuket, phi phi island and koh pangnon.