Karmactive Staff
The National Weather Service has issued a Coastal Flood Advisory for the San Francisco Bay Area from 7 p.m. Monday, July 21, through midnight Tuesday, July 22, covering the North Bay Interior Valleys, San Francisco Bay Shoreline, and San Francisco County, with up to one foot of inundation above ground level possible in low‑lying areas.
Tonight’s peak high tide is forecast at 6.88 ft MLLW at the San Francisco tidal gauge around 9:02 p.m. PDT.
“Minor coastal flooding expected along the Bayshore tonight; flooding of lots, parks, and roads with isolated closures possible,” per the official NWS advisory.
What’s Coming Tonight
If you’ve got plans near the water, reconsider them: high astronomical tides combined with onshore winds will push water inland in vulnerable areas.
Inexperienced mariners should avoid navigating in hazardous conditions under the Small Craft Advisory.
Expect to see:
- Water ponding across shoreline parks and parking lots
- Temporary road closures in low‑lying areas
- Wet conditions on coastal trails and paths
The Boating Lowdown
A Small Craft Advisory is in effect for SF Bay north of the Bay Bridge until 9 p.m. PDT, with northwest winds 10–15 kt and seas 4–6 ft through tonight, subsiding to seas 3–4 ft after dark. Mariners should secure vessels before conditions deteriorate and heed all navigational cautions.
Similar Posts
History Repeats: The King Tide Pattern
Seasonal “king tide” events—perigean spring tides—have produced similar minor inundation along Bay Area shorelines, illustrating how lunar perigee on July 20 and the new moon on July 24 align to drive especially high tides several times a year.
Staying Dry: What To Do Now
If you’re in a flood‑prone area:
- Sandbags: Marin County provides free sandbags at designated Public Emergency Portal sites; see the interactive map at emergency.marincounty.gov/pages/sandbags.
- San Francisco sandbags: SF Public Works offers up to 10 free sandbags Mon–Sat, 8 a.m.–2 p.m., at the Public Works yard (Marin St/Kansas St gate).
- Move vehicles: Park on higher ground if your usual spot sits near the shoreline.
- Prep your home: Install door sweeps on basement entrances and elevate utilities above expected flood elevations.
- Alerts: Text your ZIP code to 888‑777 for AlertSF notifications.
- Traffic updates: Use Caltrans’ QuickMap (quickmap.dot.ca.gov) or dial 511 to check real‑time highway conditions and closures.
The Bigger Water Picture
NOAA CO‑OPS data show a mean sea‑level trend of 1.98 mm/year (≈0.65 ft per century) at the San Francisco gauge, a rise that has steadily increased the frequency and severity of minor coastal flooding over decades. Local resilience efforts—including Alameda’s Shoreline Adaptation Plan at Alameda Point and Marin County’s Shoreline Adaptation Plan—focus on living shorelines and levee improvements to buffer tidal surge.
Stay Smart, Stay Dry
Waters will begin rising around 7 p.m., peak at 9:02 p.m., and recede by midnight. Remember to:
- Avoid driving through flooded areas (12 inches of moving water can float most cars).
- Respect barricades and road closures.
- Move to higher ground if water approaches.
- Disconnect utilities if flooding reaches your property.
- Watch for electrical hazards in standing water.
Flood waters are expected to recede by tomorrow morning as the advisory ends at midnight.
