Also, because the nature of monsoons is that they come and go very quickly...DO NOT ever walk into, or drive your car into, a wash or a street where "Flash Flood" signs are posted. Moonsoons can cause floods in the blink of an eye, and inevitably every year the Fire Department has to pull a flooded car out, or someone gets trapped in their car.
Of course, don't be swimming or standing under trees during a monsoon. You don't want to be struck by lightning.
In general, though, if you use your common sense, you will be fine.
(My wedding ceremony took place during a monsoon storm. Luckily we were indoors!)