Driving in rain: hydroplaning, standing water and flood safety
How to check your tires, recover from hydroplaning and stay out of floodwater
Picture the first storm after weeks of dry, hot weather. The road looks only damp. Yet the car ahead stops sooner than you expect. Your tires feel vague in the next curve. A few miles later, brown water covers a low spot ahead.
Rain is the most common weather factor in U.S. crashes. From 2019 to 2023, crashes during rain killed an average of 2,810 people a year, the Federal Highway Administration (FHWA) reports [1]. That is nearly 8 deaths a day (our calculation).
Floodwater adds a separate danger. Citing federal health data, the National Weather Service (NWS) reports that over half of flood drownings happen when someone drives into hazardous floodwater [2].
This guide shows how to prepare, how to react if you hydroplane and when to turn back.
Rain by the numbers: the deadliest weather on the road
Using National Highway Traffic Safety Administration (NHTSA) data from 2019 through 2023, FHWA reports that weather related crashes averaged about 745,000 a year, or 12% of all crashes [1]. Of those, 574,047 a year happened during rain or mist [1].
That means rain accounts for about 77% of weather related crashes, 74% of the deaths and 82% of the injuries (our calculations from FHWA figures) [1].
Rain cuts both pavement friction and visibility, yet drivers adjust only a little [1]. In light rain or snow, average freeway speeds drop just 3% to 13%, FHWA reports [1]. At 65 mph, a 3% drop is only about 2 mph (our calculation).
Why wet roads lose grip
Your tires hold the road through a few palm sized patches of rubber. On a wet road, a film of water sits between that rubber and the pavement. The grooves in your tread act like channels that push it aside.
When water builds up faster than the tread can clear it, the tire lifts off the pavement and rides on the water. That is hydroplaning. It can cost you steering and braking control [5].
Pennsylvania’s driver’s manual warns that hydroplaning can start at 35 mph in water just 1/10 inch deep. Worn tires make it worse [4]. New York’s manual adds that underinflated tires raise the risk, too [5].
Why the first rain is the slickest
California’s handbook says oil and dust left on the road during dry, hot spells have not yet washed away [3]. Pennsylvania’s says pavement can get very slippery in the first 10 to 15 minutes of a storm. Heat makes it worse [4].
Heavy rain eventually rinses the surface, but a wet road never grips like a dry one. Road weather specialists treat the first drops, not the first skid, as the cue to slow down.
Tires: check the tread before it rains
Tread is what lets tires grip on wet or icy roads. NHTSA says tires are unsafe once tread wears down to 2/32 inch [7]. Legal tread, however, is not the same as good rain tread.
In a 2018 AAA study, all season tires worn to 4/32 inch added an average of 87 feet to a car’s wet stopping distance from 60 mph [8]. That is almost 6 car lengths, assuming a 15 foot car (our calculation). When cars on new tires had stopped, those on worn tires were still moving at about 40 mph. So AAA recommends replacing tires at 4/32 inch [8].
Comparison compiled by Safety Behind the Wheel Foundation
| Quick check | What you see | What to do |
|---|---|---|
| Quarter, Washington’s head down in a groove | All of his head | Start shopping for tires, per AAA [8] |
| Penny, Lincoln’s head down and facing you | All of his head | Replace the tires [7] |
| Built in treadwear bars | Tread level with the bars | Replace the tires [7] |
| Pressure gauge, tires cold | Below the door label number | Inflate to the pressure on the driver’s door edge [7] |
NHTSA advises checking tread and pressure at least once a month [7].
Your rainy day checklist before you drive
Slow down, add space and leave cruise control off
Speed is the setting you control most directly. California’s handbook advises slowing 5 to 10 mph on wet roads [3]. If you can’t see beyond 100 feet, it says going faster than 30 mph is unsafe [3].
AAA suggests 5 to 6 seconds of following distance in wet weather [10], about double the 3 second gap many instructors teach for dry roads. Our guide to safe following distance shows how to count it. Brake sooner and more gently than usual [6]. Signal earlier so drivers behind you have time to react [5].
Turn cruise control off, as Oregon’s driver manual advises for wet conditions [6]. AAA explains that driving without it lets you respond quickly if the car loses traction [8].
Don’t let driver aids set your pace. In AAA’s closed course tests in simulated rain, cars with automatic emergency braking hit a stopped target in 33% of runs at 35 mph [10]. Lane keeping systems drifted out of the lane 69% of the time [10].
See and be seen: headlights, wipers and a clear windshield
Rain makes it harder for you to see out and for others to see you [5]. Use low beams, because high beams reflect off falling rain and cut your view, New York’s manual explains [5].
The easiest habit is “wipers on, headlights on,” which Oregon’s manual recommends [6]. Don’t rely on daytime running lights or automatic headlights. Pennsylvania’s manual says daytime running lights don’t satisfy its law and that taillights must be on, too [4].
Use your defroster as well [3]. Your owner’s manual shows the fastest defog setting. Big trucks throw off sheets of spray, so pass them steadily or drop back until you can see.
What to do if you hydroplane
You usually feel hydroplaning before you see it: the steering suddenly goes light. The engine may also rev as the drive wheels lose grip. California’s handbook says sloshing sounds from your tires are a signal to slow down [3].
Rehearse these steps aloud until they become automatic:
- Keep your foot off the brake at first, since sudden braking can make you lose control [3, 4].
- Ease off the gas, lifting your foot slowly so the car slows on its own [4, 8].
- Hold the wheel steady with both hands. Keep the front wheels pointed where you want to go. Look at that path rather than the hazard [4, 8].
- Wait for the tires to grip, and when the steering firms up, make only small, smooth corrections [4].
- Brake gently if you must slow more [4]. If the wheels lock in a skid and you have four wheel antilock brakes (ABS), California’s handbook says to press firmly on the pedal [3].
- Slow down more once you regain control, as New York’s manual advises after any loss of traction [5].
Standing water: steer around, slow down or turn back
Floodwater: why you should always turn around
Flooding kills more people each year than any other thunderstorm hazard, NWS reports [2]. Its campaign name, Turn Around Don’t Drown, is also the safest driving rule there is.
Moving water is far stronger than it looks. NWS says 6 inches of fast moving water can knock over an adult. It adds that 12 inches of rushing water can carry away most cars [2]. Once water lifts a vehicle, its steering and brakes stop working.
A study of U.S. flood deaths from 1959 to 2019 found vehicles were involved in 57.8% of deaths with known circumstances [12]. About half of all the deaths happened at night [12]. Only 59% of records listed circumstances, so treat these shares as estimates [12].
When water covers a road, NWS points out, you can’t know its depth or the state of the road beneath it, especially at night [9]. The road may have collapsed [2]. The water can also hide debris and downed power lines [3]. The study’s authors link the many nighttime deaths to flash floods that rise fast and are hard to see in the dark [12].
If water traps your car
Official guidance offers these last resort steps:
- Call 911 if you can. Stay in the car if it is in rapidly moving water. If water rises inside, get onto the roof, advises the Federal Emergency Management Agency’s (FEMA’s) Ready.gov [13].
- Don’t try to wade out through a current, since 6 inches of fast water can knock an adult down [2].
- If the car is sinking, New York’s manual says to unbuckle and leave through a window, because an open door lets water rush in [5].
After a flood: damaged cars and hurricanes
Treat a flooded car as damaged: if water reached the floor or engine, have a qualified technician check the brakes, electrical and safety systems before you drive. NHTSA warns that flooded hybrid and electric vehicles can pose high voltage shock and fire hazards [14]. It advises parking a damaged one outside, at least 50 feet from buildings and other vehicles, and contacting the dealer or emergency services [14]. Our guides to vehicle maintenance and recalls and defects explain what to check.
Hurricanes and tropical storms. NWS reports that flooding from heavy rain is the second leading cause of deaths from landfalling tropical cyclones [15]. It can strike hundreds of miles inland and last for days [15]. If officials tell you to evacuate, go right away, before the water rises. Stay off bridges over fast moving water [9, 13]. After a flood, drive only in emergencies [13].
Advice for new drivers and parents
Rain adds work for drivers who are still building skills. Parents can fold it into a supervised practice plan:
- Build up in stages. Start with light rain in daylight on familiar roads, then add heavier rain, highways and night rain.
- Learn the controls first. A new driver should find the wipers, defroster and headlight switch without looking.
- Rehearse, don’t experiment. Talk through the hydroplaning steps, and never practice skids on public roads.
- Set a family flood rule. No one drives through water covering a road. Instead, call, wait or reroute, with no penalty for arriving late.
Frequently asked questions
Is it safe to drive through a flooded road if other cars made it?
No: NWS says it is never safe to drive into floodwater [2]. You can’t know the water’s depth or the road’s condition underneath. The pavement may have collapsed [2, 9].
How fast do you have to go to hydroplane?
It can begin at 35 mph in water 1/10 inch deep, Pennsylvania’s driver’s manual says. Worn or underinflated tires raise the risk [4, 5].
Is it illegal to drive with your wipers on and headlights off?
In some states, yes, including Pennsylvania, New York and Virginia, though the details differ [4, 5, 11]. Make “wipers on, headlights on” your habit everywhere.
When should I replace tires for driving in rain?
AAA recommends replacing them at 4/32 inch of tread [8], earlier than the 2/32 inch point at which NHTSA calls tires unsafe [7]. If you can see all of Washington’s head in the quarter test, start shopping [8].
What should I do if my car stalls in floodwater?
Call 911 if you can, and don’t try to wade through a current. Ready.gov advises staying in the car if it is trapped in rapidly moving water and getting onto the roof if water rises inside [13].
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Rain rewards drivers who decide early. Slow down at the first drops, double your following distance and keep cruise control off. Keep at least 4/32 inch of tread so water has somewhere to go. When water covers the road, don’t test it: turn around.
Related articles
- Safe following distance: the 3 second rule and when to add more
- Night driving safety: how to see hazards and stop in time after dark
- Driving in fog: safe speeds, the right lights and when to pull off
- Vehicle maintenance for safety: tires, brakes, lights and warning signs
- Vehicle recalls and safety defects: how to check, fix and report
Sources and further reading
- 1Federal Highway Administration (FHWA), Road Weather Management Program. How Do Weather Events Impact Roads? Five-year averages, 2019 to 2023, from NHTSA data as reported in May 2024. Accessed October 3, 2026. ops.fhwa.dot.gov/weather/q1_roadimpact.htm
- 2National Weather Service (NWS). Turn Around Don’t Drown. Updated September 22, 2026. weather.gov/safety/flood-turn-around-dont-drown
- 3California Department of Motor Vehicles. California Driver’s Handbook: Safe Driving. Updated June 11, 2025. dmv.ca.gov/…/safe-driving
- 4Pennsylvania Department of Transportation (PennDOT). Pennsylvania Driver’s Manual: Managing Speed. Accessed October 3, 2026. pa.gov/…/managing-speed
- 5New York State Department of Motor Vehicles. Driver’s Manual, Chapter 10: Special Driving Conditions. Accessed October 3, 2026. dmv.ny.gov/…/chapter-10-special-driving-conditions
- 6Oregon Department of Transportation, Driver and Motor Vehicle Services. Oregon Driver Manual, Section 7: Safe and Responsible Driving (Hazardous Conditions: Rain). Accessed October 3, 2026. oregon.gov/…/Study-Section_7.aspx
- 7National Highway Traffic Safety Administration (NHTSA). Tires. Accessed October 3, 2026. nhtsa.gov/vehicle-safety/tires
- 8AAA. Tread Lightly: Worn Tires Put Drivers at Risk (news release). June 7, 2018. newsroom.aaa.com/2018/06/tread-lightly…
- 9NWS. Flood Safety for You and Your Family (one-page flyer, PDF). November 2018. weather.gov/media/owlie/FloodSafety-OnePager-11-29-2018.pdf
- 10AAA. Rained Out: Vehicle Safety Systems Struggle to See in Bad Weather (news release and driving tips). October 14, 2021. newsroom.aaa.com/2021/10/rained-out…
- 11Code of Virginia. § 46.2-1030. When lights to be lighted; number of lights to be lighted at any time; use of warning lights. Last amended 2025. law.lis.virginia.gov/…/section46.2-1030
- 12Han Z, Sharif HO. Analysis of Flood Fatalities in the United States, 1959 to 2019. Water 13(13):1871. July 5, 2021. mdpi.com/2073-4441/13/13/1871
- 13Federal Emergency Management Agency (FEMA), Ready.gov. Floods. Updated October 17, 2024. ready.gov/floods
- 14NHTSA. Electric and Hybrid Vehicles (FAQ: flooded or submerged vehicles). Accessed October 3, 2026. nhtsa.gov/vehicle-safety/electric-and-hybrid-vehicles
- 15NWS. Hurricane Safety Tips and Resources. Updated June 12, 2025. weather.gov/safety/hurricane
This article reflects the safety priorities of driver safety instruction and road weather science. It is general education, not legal or professional advice for any individual. Figures marked as our calculations are simple estimates and do not predict how any specific vehicle will perform. Laws, data and vehicle features change, so verify details with official sources. Reviewed October 2026.
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