1. Rain after a long period of no rain- This can cause the oil and residues on the road to become very slick. Often several traffic accidents will occur in this situation.

2. Sun blinding- When the sun is at a low angle it is more difficult to block it out in a vehicle. This can cause loss of visibility of the road ahead.

3. Frost on windows- If all frost is not melted off windows or scrapped off windows it can cause of restriction of visibility when driving. This is especially true when it combines with a fogging up of windows.

4. Rapid fog up of windows- This can occur suddenly and it may take time for the defogger to remove this fogging up. It will cause a loss of visibility. This can occur when it is very humid outside (RH near 100%) and the car is cooled inside. Moisture condenses out once it contacts the cooler car (fogging outside of windows). Fogging up can also occur when the nearly saturated air in the car is cooled below the dewpoint of the air in the car or the moisture you breath out in the car is enough to start the fogging process since it raises the dewpoint in the car (fogging inside of windows).

5. Freezing / thawing of water in cracks in road- As water freezes it expands. This process can increase the size of cracks in the road and increase the number of potholes.

6. Snow sticking to road signs- When snow sticks to road signs it can make them more difficult or impossible to read.

7. Freezing rain- There are situations in which it freezes doors shut or freezes up key hole.

8. Raining mud- Can occur in situations where precipitation occurs near a dryline boundary that brings in blowing dust. As the precipitation evaporates it leaves behind a thick film of dirt on the vehicle. Extreme cases occur when precipitation occurs near a volcanic eruption.

9. Driving by a middle school at the end of the school day after a snowfall- Watch for lots of flying snowballs.

10. Strong wind- Strong crosswind makes driving more difficult.

11. Wet leaves on the pavement- In the fall, the leaves falling from trees can combine with moisture on the ground to produce very slick roads. Accidents can occur when the vehicle does not stop quickly enough since it slides on the wet leaves.