What Is a Flash Flood?

A flash flood is a rapid and extreme flow of water due to intense rainfall, dam failure, or other sudden water releases. Unlike gradual flooding, flash floods happen quickly, often within minutes to hours after heavy rain. Low-lying areas, highways, and city streets are particularly vulnerable.

In California, many roads are built through canyons and dry riverbeds, which can become dangerous when heavy rain falls. The California Driver Handbook warns that flooded roads may be deeper than they appear, and just a few inches of water can disable a vehicle or carry it away.

What to Do During a Flash Flood While Driving

If you find yourself on the road during a flash flood, your priority should be safety. The California Driver Handbook provides guidance on driving in hazardous conditions, emphasizing that drivers should never attempt to cross flooded roadways.

1. Turn Around, Don’t Drown

One of the most important rules to remember is: Do not drive through floodwaters. Even if the road looks passable, water depth and current strength can be deceptive. The National Weather Service reports that just 12 inches of water can float a small car, and two feet can carry away most vehicles.

If you approach a flooded road:

• Turn around and find an alternate route.
• Obey road closure signs and barricades.
• Do not assume other drivers have assessed the depth correctly.

Under California Vehicle Code (CVC) Section 22350, drivers must maintain a safe speed for conditions. If flooding reduces visibility or road safety, proceeding at normal speeds could be considered negligent or reckless driving.

2. Reduce Speed and Increase Following Distance

If heavy rain has already created standing water on the road:

• Slow down to avoid hydroplaning.
• Increase following distance to at least five seconds.
• Use low-beam headlights as required by California law when visibility is reduced.

Hydroplaning happens when tires lose traction on wet surfaces, causing the vehicle to skid. If you start to hydroplane:

• Ease off the accelerator—do not brake suddenly.
• Steer in the direction of the skid to regain control.
• Keep both hands on the wheel and remain calm.

3. If Caught in Rising Water, Exit Immediately

If water begins to rise around your car:

• Unbuckle your seatbelt and unlock doors.
• Roll down a window before power systems fail.
• If the doors won’t open, escape through the window.

If you are unable to exit, try breaking a side window with a headrest or emergency tool. California law does not mandate carrying a window-breaking device, but it is a recommended safety measure.

4. Stay Informed with Weather Alerts

California’s weather conditions can change rapidly, especially during seasonal storms. To stay updated:

• Monitor the National Weather Service (NWS) for flash flood warnings.
• Use weather apps or radio alerts to receive emergency notifications.
• Avoid driving during storms if possible.

Under CVC 38300, obeying temporary emergency signs or instructions from law enforcement during hazardous conditions is required. Ignoring flood-related road closures could lead to fines or even vehicle damage liability.

Legal and Financial Consequences of Driving Through a Flash Flood

Attempting to drive through floodwaters not only risks your safety but may also have legal and financial consequences:

• Insurance may not cover flood damage if you drove into a flooded area against warnings.
• Ignoring road closure signs could result in fines under California law.
• Rescue operations could be at your expense if emergency crews must retrieve your vehicle.

California Vehicle Code and Flash Flood Driving

Several sections of the California Vehicle Code (CVC) relate to driving in hazardous conditions:

• CVC 22350 (Basic Speed Law) – Requires drivers to adjust speed for weather and road conditions.
• CVC 23103 (Reckless Driving) – Driving through floodwaters could be considered reckless behavior.
• CVC 38300 (Obedience to Traffic Control Devices) – Ignoring flood warning signs may lead to penalties.

Stay Safe During a Flash Flood While Driving

California’s landscape makes flash flooding a real danger, particularly in low-lying areas, underpasses, and canyon roads. The best defense is prevention—avoid driving during heavy storms, turn around when encountering flooded roads, and stay informed with weather updates.

By following these safety guidelines and adhering to California’s driving laws, you can protect yourself, your passengers, and your vehicle from the risks of flash floods while driving.