Why Do Roads Get Slippery After a Summer Rain

Have you ever been on a highway on a hot summer day, and it’s been hot and very dry for weeks? Then it starts to lightly rain. You may have wondered why the road had a greasy- shiny look to it. Remember how the road got slick and slippery really fast? More Slicker than a road surface in the Winter. Why Do Roads Get Slippery After a Summer Rain?

During Hot Dry weather, residue from auto fluids, oils & rubber from tires builds up on the road. They include Asphalt Bitumen which is used in the construction & paving of roads. During the first 10-15 min of light rain, the residue makes the roads dangerous but eventually washes off the side.


There are lots of times that roadways get so slick that they become dangerous and hazardous to drive on. In the fall when the wet leaves cover up the road or the black ice that both happens here on the East Coast and this strange occurrence after a long dry spell can happen when your least expected. What happens when you skid or hydroplane or lose control-Just Don’t Panic! You got this under control.

When is the Road Most Slippery DMV


After a long dry spell and a hot summer, the highway can get extremely slippery almost greasy or oily making it dangerous and hard to drive on. The first rain makes conditions slippery for drivers because oil and grease build up on the dry roads through the summer. They form a residue that coats the top of the road mixed with a little moisture or light rain the road will become dangerous until there’s enough rainfall to wash away the residue that collected and wash it off the side of the highway.

It’s at around the first 20-30 minutes after it starts to rain is the most critical when accidents will start to occur. This is when the oils are pulled up and will float on top of the rainwater that is laying on the highway. Bitumen found in asphalt roads contributes to this.

It becomes more mobile and can sometimes ‘bleed’ through to the surface. Asphalt bitumen is non-toxic and is comprised of hydrocarbons and organic material with a high molecular density. The Bitumen is used in roofing shingles and flashing and sealants are used in construction.

Asphalt bitumen is a tar-like substance that is viscous when heated and hard when cooled. When asphalt heats to around 300 degrees, the bitumen will melt allowing it to pave a surface. Bitumen makes for a great sustainable product for paving surfaces.

These hydrocarbons are adhesive and form strong bonds with solid surfaces when at a low temperature. Crude oil deposits are formed when organic carbon material decays. Townships and cities will sometimes add sand or grit to the roadways as they do in the Winter when roadways get slick from cold temperatures.

In Summer’s hotter temperatures, the water will create a mixture of these oils, dirt, and automotive fluids that were collected in the dry spell until enough rain will wash these elements off the side of the road.  Eventually, more rain will create puddling which causes hydroplaning and loss of traction and control. Lowering your driving speed can make all the difference during a rain event. This traction normally found on highways is important for the car to hold the road.

Traction happens when the weight of a car pushing down on its tires pushes the rubber of the tire into the thousands of tiny pits and openings that make up a typical surface of a normal road. Vibrations from the surface combine with the deformation of the rubber tire to create heat, producing friction that helps the tires stick to the road. When the smallest amount of precipitation happens that friction is reduced.  Then more rain causes puddling creating a chance for your car to hydroplane.


What Is Hydroplaning


Hydroplaning is commonly used to refer to the skidding or sliding of a car’s tires across a wet surface which in the circumstance of a car is a highway. Hydroplaning occurs when a tire encounters more water than it can spread out.

Water pressure in the front of the wheel pushes water under the tire, and the tire is then separated from the road momentarily by a surface of a thin film of water and loses traction. The result is a loss of steering, braking, and power control.

Rubber tires have treads or grooves made in them that are designed to channel water from beneath the tire. This creates higher friction with the road surface and can help prevent or minimize instances of hydroplaning. Researchers say Hydroplaning can happen n any road as long as there is water but just as we were saying the most dangerous time is the first 10 or 15 minutes of a light rain especially if the vehicle is moving over 35 miles per hour.

How To Avoid Hydroplaning

The following are important tips to avoid hydroplaning:

  1. Keep your tires properly inflated
  2. Rotate and replace tires when necessary (check for worn grooves) Tires should have 2/32nds of an inch tread depth in order to perform in the way for which they were designed. Proper tread depth will help prevent skids and hydroplaning.
  3. Slow down when roads are wet because the faster you drive, the harder it is for your tires to scatter the water that lay on the roadway
  4. Avoid  puddles and standing water
  5. Avoid driving in outer lanes on the edge of the road where water tends to accumulate
  6. Try to drive in the tire tracks left by the cars in front of you
  7. Turn off the cruise control
  8. Drive in a lower gear
  9. Avoid hard braking pump your brakes, if you have an anti-lock braking system (ABS). Instead, apply pressure to the brakes in a firm manner and steer the car in the direction of the skid.
  10. Try not to make sharp or quick turns


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How to Correct a Skid

If you have been driving for a while then most likely you have Hydroplaned or lost traction and control of the car hopefully everything turned out alright other than scaring the daylights out of you. Your first reaction is probably to do the wrong thing. So in this situation,

  • Take a breath and don’t panic.
  • Keep your eyes focused on a target in the distance. Choose a point further down the road, in the direction you are headed, and stay focused on this object. With this target in view, you’ll be better able to redirect your car so that it is once again traveling in the right direction.


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Constant changes in weather are the result of changes in temperature, air pressure, and humidity in the atmosphere that result in strong winds and storms that develop and move in continuous motion keeping weather constantly changing along with seasonal changes as the earth revolves around ……………………………………………………………………… Read more



There are 2 Different Types of Skidding:

A four-wheel skid occurs when the entire car starts drifting in a direction other than the driver’s intended course.

  • This type of skid happens when a driver enters a curve too quickly.
  • If your car enters a front-wheel skid, ease off the accelerator. If you are driving a car with a manual transmission, depress the clutch.
  • With your eyes focused on your “target”, try to steer the car back on course.
  • If you don’t regain control of the car within 2-3 seconds,  depress the brake lightly.
  • If your car doesn’t have anti-lock (ABS) brakes, pump the brakes lightly.
    Braking will help to transfer power to the front of the car braking too quickly and can cause the wheels to lock, which will make the skid worse.


A rear will skid occurs when the back end of the car slides out sideways to the right or left; this is also known as fishtailing.
At some point in your life, at least one person has probably been toward you if not by accident then on purpose.

  • If the back end of your car suddenly slides out to the right you don’t want to turn your wheel sharply to the right as well, especially if you are traveling at a high speed.
  • You want to turn to the right just enough to straighten out the car and bring the front wheels back in line with the rear wheels. This is why focusing on a target is helpful it prevents you from over-correcting or overcompensating. As you turn, slowly ease off the accelerator.
  • Avoid the temptation to brake suddenly.


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Tropical storms are named by the World Meteorological Organization (WMO) and picked from a list that rotates every year for 6 years if they display a rotating circulation pattern & wind speeds reaching 39 miles per/hr & when the tropical storm’s wind speeds go above 74 mph its develops into a hurricane .………………………………………………………………….. Read more


   JimGalloway/Author Editor



Safe Motorist. com-Hydroplaning Basics: Why it Occurs and How You Can Avoid it


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