I live on Oahu. The weather changes constantly and even on a great day it could be raining in the area you are in. I suggest if you are at KoOlina and it's raining that you take a drive to Kailua or in Waikiki, try the North Shore.

Nobody can predict what the weather will be like during your stay. Be prepared to make the best out of the weather that day. If you have kids try some indoor things like the Bishop's Museum or the Waikiki Aquarium (both good options if you are sunburnt too).

Stay out of the water if signs are posted. Our beaches are sometimes contaminated after heavy rains from runoff.

Wish Hawaii was sunny every day, but it isn't.