I was going to pop over to Pulau Batam, Indonesia (a 45 minute ferry ride) for a few hours today, but not in this weather. Visa-on-arrival for US$10 for 7 days (slightly more for a longer visa) for many nationalities at many ferry terminals and airports in Indonesia.
Though it may clear up a bit around lunchtime, in which case it will still be doable…
This island was suggested by Singaporean Sue and her friends at dinner last night (no, she does not go by “Singaporean Sue”, that’s just how the sentence ran 
since it’s a shorter ferry ride from a more convenient ferry terminal (vs the 2 hour ferry ride one-way I was considering to Pulau Bintan).