In what weather condition is asphalt most slippery?

Asphalt becomes most slippery in hot weather with tar bleeding because the heat causes the tar within the asphalt to soften and seep to the surface. When this occurs, a thin layer of tar can create a slick, greasy surface, reducing tire traction significantly. This condition can be particularly dangerous for vehicles, as the presence of pooled tar can lead to loss of control, especially during acceleration or sharp turns.

While other weather conditions can also affect the road surface, such as rain making asphalt slippery due to water mixing with oils previously on the road, it is the combination of heat and the bleeding of tar that presents a uniquely hazardous situation specifically in hot weather. Cold weather does make surfaces slippery through the formation of ice, and fog, while it reduces visibility, does not inherently change the traction of the road surface.