When are the roads most slippery during rain?

Roads are most slippery during rain in the first few minutes after it starts raining. This is particularly true after a prolonged dry spell, as the rain lifts oil and other substances that have accumulated on the road surface, creating a slick layer that reduces traction for vehicles123. The initial period, typically within the first 10 to 30 minutes, is the most hazardous due to this buildup of oil and debris12. As the rain continues, it gradually washes away these substances, reducing the slipperiness over time23. Additionally, if temperatures are near or below freezing, the risk of black ice forming adds to the danger2.

Here are some key points to consider:

• Initial Rainfall: The first 10 to 30 minutes after rain starts are the most slippery due to oil and debris on the road12.
• Dry Spells: Roads are particularly slippery after a long dry period because there's more oil and debris accumulated34.
• Temperature: If temperatures are near or below freezing, black ice can form, making roads even more hazardous2.

To stay safe, it's advisable to slow down, increase following distances, and avoid sudden maneuvers when driving in these conditions124.