San Francisco and San Mateo counties are the focus of a flood advisory issued at 4:19 a.m. on Monday by the National Weather Service. The advisory is in effect until 6:15 a.m.

The NWS San Francisco CA said, “Flooding caused by excessive rainfall is expected.”

“Minor flooding in low-lying and poor drainage areas,” the NWS said. “Turn around, don’t drown when encountering flooded roads. Most flood deaths occur in vehicles. Please report observed flooding to local emergency services or law enforcement and request they pass this information to the National Weather Service when you can do so safely.”


How to use a sandbag and where to get sandbags in your area:

Follow these instructions on how to use sandbags and other flood preparation tips to protect your home, and click on the links below to get sandbags in your county:

Where to get sandbags in San Mateo County

Where to get sandbags in Alameda County

Where to get sandbags in Santa Clara County

Your guide to weather alerts: advisories, watches, and warnings

Flash flood warning: Take action!

A flash flood warning is issued when a flash flood is either imminent or already occurring. In flood-prone areas, it’s crucial to move immediately to higher ground. A flash flood is a sudden and violent inundation that can develop within minutes to hours, and it can even happen in areas not currently experiencing rainfall.

Flood warning: Take action!

A flood warning is declared when flooding is on the verge of happening or is already underway.

Flood advisory: Be aware:

A flood advisory is issued when flooding is not expected to be bad enough to issue a warning. However, it may cause significant inconvenience, and if caution is not exercised, it could lead to situations that may threaten life and/or property.

Flood watch: Be prepared:

A flood watch is issued when conditions are favorable for flooding. It does not mean flooding will occur, but it is possible.

Keeping safe during floods: Expert advice from the NWS

Floods can pose a significant threat, especially if you live in a flood-prone area or find yourself camping in a low-lying region. To ensure your safety, the NWS offers essential flood safety guidelines:

Seek higher ground:

If you reside in a flood-prone region or are camping in low-lying terrain, the first step to safety is relocating to higher ground.

Follow evacuation orders:

When local authorities issue an evacuation order, promptly comply. Before leaving, secure your home by locking it.

Disconnect utilities and appliances:

If time permits, disconnect your utilities and appliances. This precaution minimizes electrical hazards during flooding.

Avoid basements and submerged areas:

Steer clear of basements or rooms where water has submerged electrical outlets or cords. This helps prevent electrical accidents.

Swift evacuation for your safety:

If you notice sparks or hear buzzing, crackling, snapping, or popping sounds, evacuate without delay. Do not enter water that may carry an electrical charge.

Stay away from floodwaters:

Never attempt to walk through floodwaters, even if they appear shallow. Just 6 inches of fast-moving water can forcefully sweep you off your feet.

Seek high ground if trapped:

In the event you become trapped by moving water, make your way to the highest point available and contact emergency services by calling 911.

When heavy rain occurs, there is a risk of flooding, particularly in low-lying and flood-prone regions. It is important to never attempt to drive through water on the road, regardless of how deep it appears. According to the NWS, as little as 12 inches of rushing water can sweep away most vehicles. Prioritize your safety by staying informed and prepared.

Mastering wet roads: Safety tips for heavy rainfall

When heavy rain pours, the risk of flooding and treacherous roads rises. Here’s your guide from the NWS to staying safe during downpours:

Beware of rapid water flow:

Avoid parking or walking in close proximity to culverts or drainage ditches, as the swiftly moving water during heavy rain can potentially carry you away.

Maintain safe driving distances:

The two-second rule for following distance is your ally in heavy rain. Extend it to four seconds to ensure safe spacing in adverse conditions.

Slow down and stay cautious:

If it is raining and the roads are wet, slow down. Take your foot off the accelerator and let your speed drop gradually. Never use the brakes suddenly because this may cause the car to skid.

Choose your lane wisely:

Stick to the middle lanes to minimize the risk of hydroplaning. Outer lanes are more prone to accumulating water.

Prioritize visibility:

Enhance your visibility in heavy rain by turning on your headlights. Watch out for vehicles in blind spots, as rain-smeared windows can obscure them.

Watch out for slippery roads:

Be extra careful during the first half hour after rain begins. Grime and oil on the road surface mix with water to make the road slippery.

Keep a safe distance from large vehicles:

Don’t follow large trucks or buses too closely. The spray created by their large tires reduces your vision. Take care when passing them as well; if you must pass, do so with caution.

Mind your windshield wipers:

Overloaded wiper blades can hinder visibility. If rain severely impairs your vision, pull over and wait for conditions to improve. Seek refuge at rest areas or sheltered spots.
If the roadside is your only option, pull off as far as possible, preferably past the end of a guard rail, and wait until the storm passes. Keep your headlights on and turn on emergency flashers to alert other drivers of your position.

By following these safety measures, you can significantly reduce risks and ensure your well-being when heavy rain pours down. Stay informed about weather conditions and heed advice from local authorities to make your journey safe and sound.

For more weather alerts in the Bay Area, visit Weather Advisories