When is it most important to be cautious about turning and stopping due to rain?

The first half hour of rain is a critical time for drivers to be particularly cautious about turning and stopping because during this period, water can mix with oil and grime that have accumulated on the road surface. This mixture creates very slippery conditions, significantly increasing the risk of skidding and loss of control. As rain begins to fall, the road's traction decreases, making it essential for drivers to reduce their speed, increase their following distance, and be vigilant when making turns or stopping.

As rain continues, while conditions can remain wet and potentially hazardous, the initial layer of oil and contaminants is washed away, improving traction slightly. Therefore, the initial period of rain poses the greatest risk for drivers, necessitating increased caution.