Flash Flood and Severe Thunderstorm Threat Expands Across San Bernardino County
A dangerous combination of heavy rainfall, thunderstorms and rapidly developing flooding is affecting parts of San Bernardino County in Southern California. Residents and travelers should remain alert as multiple weather alerts highlight the potential for hazardous conditions.
A Flash Flood Warning is in effect for parts of San Bernardino County, while a Severe Thunderstorm Warning covers western portions of the county. In addition, a Flood Advisory is highlighting the potential for nuisance and potentially hazardous flooding in the area.
Multiple Weather Threats Are Developing
The combination of these alerts means conditions can change quickly.
Flash Flood Warning
A Flash Flood Warning indicates that flash flooding is occurring or imminent in the warned area. Water can rise rapidly in normally dry washes, low-water crossings, streets and drainage channels.
Residents should avoid driving through flooded roadways. Even shallow moving water can sweep vehicles off the road.
Severe Thunderstorm Warning for Western San Bernardino County
Western San Bernardino County is also under a Severe Thunderstorm Warning, signaling the potential for dangerous thunderstorms.
Severe thunderstorms can bring:
- Damaging wind gusts
- Frequent lightning
- Torrential rainfall
- Sudden flooding
- Hail in stronger storms
- Dangerous driving conditions
Thunderstorms may also produce intense rainfall in a short period, increasing the risk of flash flooding.
Flood Advisory
A Flood Advisory is also in effect for San Bernardino County, indicating that rainfall and runoff may produce localized flooding.
Although an advisory is generally less urgent than a warning, conditions can deteriorate quickly when additional thunderstorms develop over already-wet areas.
Why Flash Flooding Can Be Dangerous in Southern California
Southern California’s landscape can make flash flooding particularly dangerous. Dry washes, channels and low-lying areas can fill rapidly when thunderstorms release heavy rainfall.
Water may also flow into areas that are not experiencing heavy rain directly. Runoff from higher elevations can move downstream toward roads, neighborhoods and drainage areas.
Never attempt to cross a flooded road or wash. Turn around and find another route.
San Bernardino County Residents Should Stay Weather Aware
As thunderstorms continue, residents should monitor changing conditions and be prepared to move to a safer location if flooding threatens.
If you are outdoors, move indoors when thunder is heard. Stay away from washes, creeks, drainage channels and other areas where water can rapidly accumulate.
Drivers should use extra caution because heavy rain can dramatically reduce visibility and create standing water on roadways.
What to Do During a Flash Flood
If a Flash Flood Warning affects your location:
- Move to higher ground immediately if flooding is approaching.
- Stay away from washes, rivers, creeks and drainage channels.
- Never drive through moving or unknown-depth water.
- Avoid flooded underpasses and low-water crossings.
- Follow evacuation instructions from local officials.
- Keep phones charged so emergency alerts can be received.
- Do not walk through moving floodwater.
Stay Alert as Storms Move Across Southern California
The situation can evolve rapidly as thunderstorms develop and move across the region. A location that is dry now can experience dangerous flooding later if heavy rainfall develops upstream.
For San Bernardino County residents, the combination of a Flash Flood Warning, Severe Thunderstorm Warning and Flood Advisory makes continued weather awareness especially important today.
Stay Ahead of the Storm With Radar Watch HQ
Weather conditions can change in minutes. Follow Radar Watch HQ for continuing severe weather updates, storm alerts, wildfire conditions and other important weather developments across the United States.
Stay weather aware, avoid flooded roads, and never risk your life trying to cross moving water.
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Radar Watch HQ Top 5 Essential Emergency Preparedness Picks
Whether you’re preparing for severe thunderstorms, flash flooding, hurricanes, wildfires, or extended power outages, these five emergency essentials can help keep your household safer when severe weather strikes.
A portable power station provides reliable backup electricity during outages, allowing you to power phones, medical devices, laptops, lights, small appliances, and communication equipment without fuel.
Best for:
- Extended power outages
- Severe thunderstorms
- Hurricanes
- Winter storms
- Wildfires
2. Flood Protection Barriers & Sandless Flood Bags
Flood barriers help divert or absorb water before it enters garages, doorways, and low-lying areas. They deploy quickly and can help reduce property damage during flash flooding.
Best for:
- Flash Flood Warnings
- Heavy rainfall
- River flooding
- Coastal flooding
3. Rechargeable LED Flashlights
Bright, dependable flashlights are essential when the power goes out. Rechargeable or solar-powered models provide long-lasting illumination for navigating safely indoors and outdoors.
Best for:
- Overnight power outages
- Emergency evacuations
- Storm damage inspections
Keep phones, tablets, weather radios, and USB-powered devices charged when the electrical grid is unavailable. A solar power bank offers an additional charging option during prolonged emergencies.
Best for:
- Communication during outages
- Emergency weather alerts
- Travel and evacuation
A NOAA Weather Radio delivers official weather alerts directly from the National Weather Service, even when cellular networks or internet service are unavailable. It remains one of the most dependable ways to receive life-saving warnings.
Best for:
- Tornado warnings
- Severe thunderstorm warnings
- Flash flood warnings
- Hurricane alerts
- Winter storm emergencies
Why Radar Watch HQ Recommends These Essentials
At Radar Watch HQ, preparedness is just as important as staying informed. These five emergency essentials can help you stay connected, protect your property, and safely navigate severe weather events. Having supplies ready before storms arrive allows you to respond quickly when warnings are issued and conditions begin to deteriorate.
