Mumbai is worst city during the monsoons as:
- it gets very heavy rainfall during monsoon
- Most of its area have very low altitude
- it gets sudden torrential rains for a short period like 2-3 days
-...
more... very dense population and shortage of drainage facilities
- Choking of drains lead to water logging and large area gets inundated
- above all high tides have multiplier effect to the above woes.