When should you be particularly cautious of slippery roads?

Being particularly cautious of slippery roads when it first starts raining is due to the initial encounter between rain and accumulated oils and debris on the road surface. During dry weather, oils and other pollutants can build up on the pavement, and when it begins to rain, the water causes these substances to rise to the surface, creating a slick and hazardous layer. This condition makes the roads much more slippery for drivers, significantly increasing the risk of losing traction.

As the rain continues, the water helps to wash away some of these contaminants, gradually improving road traction. Therefore, the first few minutes of rain are critical for drivers to exercise caution. Understanding this dynamic is essential for safety, as it highlights the need for reduced speed and increased awareness right at the onset of rain.

Other conditions mentioned can pose their own hazards, but the immediate danger upon the start of rainfall is particularly acute due to the interaction between rainwater and road contaminants.