It seems to me that weather has been varying quite a bit of late, with lots more rain than usual, thus the report that you heard. Bonaire has had much more rain than usual, (it is typically desert) but it's to soon to "pattern" it, IMO. Even with more rain there is rain, then sun, rain, more sun, more sun, etc etc.
My solution is to be underwater all the time then I don't care what the weather is!
Typically the main Bonaire weather variable is the wind - 10 months out of the year the east-west trade winds blow at about 20 MPH non-stop. In September and October they tend to die down, which means you
feel the heat alot more.
I emphasize
feel because Bonaire average temp doesn't vary by more than a few degrees year around, being a few degrees north of the equator.
If it's been raining alot, and if you're in an area with lots of standing water you might get some mosquitos in the evening, and should prepare accordingly. Unless you're really sensitive don't worry about it, just be prepared. If you react to mosquito bites make sure you're prepared to deal with them.
OH, and with ticket prices as of late, a mileage ticket is worth a LOT! Prices have gone up quite a bit recently.
You should have a wonderful time in December, or any other time you visit Bonaire!