Reading in Dimmitt et al.'s book on Adeniums regarding flowering I summarize as best as I can:
When night time lows are above 60F and day time highs above 80F you can water most Adeniums pretty heavily without problems as long as it is in well draining soil as many others have already mentioned.
Drought conditions or plants that are underwatered will stop them from blooming or abort the blooming process. Temperatures consistently above 99-104F will also put a halt to blooming in most species (I experience that every summer...).
Also when the plant is actively growing it will also be less inclined to bloom, most Adeniums have their active growing season in summer.
Most Adeniums need it to be warm and require lots of bright (when possible direct) sun light to flower consistently.
In the tropics plants may have to be protected from excessive rainfall, and excessive cloud cover can be a problem (ie. not enough bright light) for good growth and flowering. So the rain may not have been the problem so much as the lack of brightness that the clouds would have caused.
They flower best in Spring and Fall when it is warm and the plant is in bright light - here in the desert I need to keep them somewhat shaded, but in many places they should be able to take pretty much full sun (acclimatize them slowly if they have spent a lot of time in shaded conditions). However most easily available cultivars can easily flower 9 out of 12 months of the year in the right conditions.
