When are roadways typically most slippery?

Roadways are typically most slippery during the first rain after a dry spell due to the combination of oil and debris that accumulates on the road surface. When rain first falls after a prolonged dry period, it mixes with this buildup, creating a slick layer on the pavement. This can make it particularly hazardous for drivers, as the water can cause the oil to rise to the surface, leading to reduced traction.

While heavy snowfall and rainstorms can also create slippery conditions, the initial rainfall after dry weather poses a unique challenge because the road has not yet absorbed moisture, and the slick film from the oil and debris is still present. After it rains heavily or during continuous snowfall, the roads may become slippery as well, but typically the level of slickness is heightened the first time rain hits a dry surface.