Even a light rain could make the roads more dangerous. Everyone knows water can make the roads slicker, but rain on roads is a different level of hazard because oils from tires and cars cause an extra layer of slickness making it harder for tires to maintain traction. This could lead to hydroplaning, which occurs when the tires cannot push water away faster than it accumulates in front of them. This results in a car sliding over the road without the driver being able to control it. Hydroplaning may be even more likely when vehicles are traveling at high speed and the brakes are applied.
There is a common misconception that there needs to be a lot of water on the road for you to hydroplane. However, it does not take much water to hydroplane especially with roads oils blended in.
Wet roads can make it harder for vehicles to stop as quickly. When drivers hit the brakes, their cars slide further than normal before coming to a complete stop. The front of the car could end up in the intersection instead of behind the white line. Drivers could end up crashing into the rear of another vehicle because their car did not stop as quickly as it normally would on a dry road.
The first 10 minutes of rain on a road is the worst because of the oil.