ROADS BECOME VERY SLIPPERY:
Right after the rain has stopped
For the first 10 to 15 minutes of a rain storm
When it has been raining for an hour or more
The day after it rains
After the rain has stopped, roads can become very slippery due to the build-up of oils and debris on the surface. This is especially true in the first 10 to 15 minutes of a rainstorm, as the water mixes with these substances, creating a slick surface. Additionally, roads can be extremely slippery when it has been raining for an hour or more, as the water continues to accumulate and saturate the roadways.
Even the day after it rains, roads can still be slippery as there may still be residual water on the road surface. It's important to exercise caution and drive carefully in these conditions to avoid accidents.