When do roads become particularly slippery during rain?

Roads become particularly slippery during the first 10 to 15 minutes of a rainstorm because this is when the rain starts to mix with the oil and debris that has built up on the road surface. When it begins to rain, the water lifts the oils and other substances from the pavement, creating a slick layer that can significantly reduce traction for vehicles. Drivers should be especially cautious during this initial period, as it poses a higher risk of hydroplaning and loss of control.

As the rain continues, the water may wash away some of the oils and debris, which can improve traction later in the storm. Conversely, waiting until after the rain has stopped, or the next day when the pavement has dried, doesn't present the same immediate slippery condition that occurs when the rain first begins. Understanding this principle is crucial for maintaining safety and control while driving in wet conditions.