I have done some research on the topic a few months ago, and this is what I found; When rain or standing water beads up between your tires and the road your car begins to glide uncontrollably, which is called hydroplaning. This is one of the more dangerous situations to find yourself living out. The steering wheel feels loose, unresponsive and you have lost steering control of your forward moving vehicle...this is a very bad situation. Your best chance for an effective outcome is to lift your foot from the accelerator pedal and slow down. Do not put your foot on the brake. Continue driving at a slower speed keeping the car heading in the right direction as much as is possible (you may feel the car drifting, but don't freak out). As the car slows down the weight becomes more dense and gravity will push the vehicle tighter to the road surface, allowing you to gain back some steering control. Eventually the car will return completely back to your control. If the rain or weather becomes far to heavy, you need to pull off of the road into a rest stop, gas station or any other populated location. If nothing is around pull over to the side of the road and turn on your hazard lights so other drivers can see you. When the rain subsides continue safely on your way.
Something worth mentioning is that deep-tread tires sluff off the excess water while low tread or worn tires trap the water increasing the hydroplaning probability. Keeping your tires in good condition and running on the proper tire for the season can help prevent hydroplaning.
Hope this helpls.