On September 10, 2026, NOAA's Climate Prediction Center put an El Niño Advisory in effect and gave a greater than 90% chance of a very strong El Niño this fall and winter.1 El Niño raises the odds of a wet winter in California. It does not guarantee one. Either way, the dry weeks before the first big storm are the cheapest time to find where water could get into a house.
- Most rain leaks start at the same few places: gutters, roof flashing, and old caulk around windows and doors.
- Look from the ground and from the attic. You do not need to climb onto the roof to spot most problems.
- Valley Water gives Santa Clara County residents free sandbags from November 1 through April 15.2
- Sign up for AlertSCC and report blocked storm drains to the City at 408-794-1900 or 311.3
1. Clear the gutters and downspouts
A clogged gutter overflows at the eaves and dumps water against the fascia, the siding and the foundation. Clear the leaves, then run a hose into each gutter and watch where the water goes. It should drain to the downspouts without spilling over, and each downspout should empty away from the house, not against the wall. Look for seams that drip and gutters that have pulled away from the fascia.
2. Look at the roof from the ground
From the yard or the street, look for missing, cracked or curled shingles, and for tiles that have slipped. Pay attention to the places where the roof meets something else: chimneys, skylights, vent pipes, and walls that rise above a lower roof. That flashing is where most roof leaks start. Branches that rub on the roof or hang over it are worth trimming before the wind arrives.
3. Reseal caulking around windows and doors
Caulk dries out and cracks in the sun. Walk around the outside of the house and look at every window frame, door frame, trim joint, hose bib and pipe that goes through a wall. If the caulk is cracked, missing or pulling away, water can follow it inside. Inside the house, check window sills and the floor just inside exterior doors for old stains or soft spots.
4. Check the attic, and check it again after the first rain
With a flashlight, look for daylight around vent pipes, water stains on the rafters and roof sheathing, and wet or matted insulation. Bathroom and kitchen fans should vent outside, not into the attic. After the first real rain, go back up and look again. A fresh stain on the wood tells you exactly where to look on the roof.
5. Keep the street drains clear
The City of San José inspects and cleans its 32,200 storm drain inlets and 30 stormwater pump stations each year before the storm season.3 Leaves still pile up once the rain starts. If the drain in front of your house is blocked, or the street is flooding, report it at 408-794-1900 or 311. Call 911 for downed power lines.3
6. Get sandbags before you need them
Valley Water gives Santa Clara County residents free filled sandbags from November 1 through April 15. In San José, the sites are the City Central Service Yard at 1661 Senter Road and the Winfield Warehouse on Winfield Boulevard. Some sites ask for proof of residency.2 The City recommends sandbags to route water away from buildings.3
7. Know your flood risk and sign up for alerts
Valley Water's Get Flood Ready page shows how to check whether your home is in a FEMA flood zone.4 Valley Water also posts live creek levels and rain gauge readings.5 Sign up for AlertSCC, Santa Clara County's free emergency alert system, to get flood and evacuation warnings.3
San José has flooded before. In February 2017, Coyote Creek crested at 13.6 feet, above its 1922 record of 12.8 feet, and the evacuation zone covered an area where about 14,000 people live.6
8. Make a plan for the house
Know where your main water shutoff is and make sure it turns. The City's storm guidance also suggests planning for power outages, raising furniture on the ground floor if water may come in, and keeping a bag ready with documents, medicines and spare clothes.3
What our free El Niño storm check covers
If you would rather have someone else look, our free El Niño storm check covers 50 points inside the house where water shows up first: ceilings, the attic, exterior walls, windows and doors, floors, wet rooms, and the garage and crawlspace. We then give you a preliminary estimate for the roof, gutters, siding and caulking. Roofing is done by our licensed C-39 subcontractor.
Sources
- 1. NOAA Climate Prediction Center: ENSO diagnostic discussion, issued September 10, 2026
- 2. Valley Water: sandbag sites
- 3. City of San José: storm preparedness (AlertSCC signup: oem.santaclaracounty.gov)
- 4. Valley Water: Get Flood Ready
- 5. Valley Water: real-time creek and rain data
- 6. Press Democrat, February 22, 2017: flooding in San Jose