Roads become very slippery:

Pavement can become very slippery within the first 10 to 15 minutes of a rainstorm because the rain causes oil in the asphalt to rise to the surface of the road. This problem becomes even worse in hot weather. The heat combined with the water causes more oil to rise to the road surface.

• When it has been raining for an hour or more.
• The day after it rains.
• For the first 10 to 15 minutes of a rainstorm.
• Right after the rain has stopped.