I aim to make my services as stress free as possible, so if you have to reschedule I will do everything within my effort to accommodate!
The Hawaiian islands have what is called microclimates - which means that you can travel to a different part of the island and experience completely different weather and scenery. We do experience a lot of rain, but it usually does not last all day and all over the island. Make sure you have a team that is willing to pivot locations in bad weather.
If you are worried about this or traveling during very rainy months (usually December - March) I would suggest an All Inclusive Elopement Package as having your officiant + photographer bundled really cuts down on logistics when it comes to a reschedule!