How to Prepare Your Home for El Niño in San Jose This Winter

This could be one of the strongest El Niño winters anybody has measured. NOAA’s October 2026 update gave it an 83% chance of beating every El Niño on record back to 1950 for the October to December stretch. The last big one, in 2015, still left San Francisco with a fairly normal rain year. Both things are true. So I’m not telling you to panic. I’m telling you to do the boring stuff, now.

I’m third-generation South Bay. I grew up in Almaden, went to Leland High School, and my family was here before this place was called Silicon Valley. These are the five things I do to my own place before the rain shows up, and most of them belong on your list every fall, rain or no rain. El Niño just puts a deadline on it.

I walked through every step on camera. Here’s the written version with the dates, sandbag sites, and links.

How Strong Is This El Niño, Really?

NOAA’s Climate Prediction Center said on October 8, 2026 that a strong to very strong El Niño is likely through January to March 2027. It put the odds of a historic event, stronger than anything since 1950, at 54% for September to November, 83% for October to December, and 70% for November to January. You can read the full NOAA discussion here.

Valley Water has already declared its own El Niño emergency for Santa Clara County this fall and stocked 24,000 sandbags across its five sites. A strong El Niño raises the odds of a wet winter. It doesn’t guarantee one. Either way, the prep below costs a weekend and a few hundred dollars at most.

Step 1: Clean the Gutters and Follow the Water

Most people stop at the gutter. I want you to follow the water. Rain hits the roof, runs into the gutter, goes down the downspout, and then what? If that downspout dumps right next to your house, you just moved the water from the roof to your foundation.

• Pull the leaves out and run a hose through every gutter and downspout.
• Make sure each downspout pushes water a few feet away from the house. An extension runs about $10 to $20 at the hardware store.
• Check whether your yard slopes away from the house or toward it.
• Rake out the storm drain in front of your house. They get buried in leaves every fall, and a clogged one sends water into your street, driveway, and sometimes your garage.

In a condo or townhome, a lot of this is the HOA’s job. I’d still walk it. You’ll spot a clogged gutter before they do.

Step 2: Check the Roof and Trim the Trees

Stand across the street and look at your roof. Look for missing shingles, cracked tiles, or anything lifted around the vents or chimney. Binoculars work. A drone works even better. Please don’t climb up there in November.

Then look at your trees. If a tree is overgrown, I’d get it trimmed, period. When it rains, leaves and branches soak up water and get heavy. The ground gets soaked and the roots lose their grip. Then the wind shows up. If there’s a dead branch hanging over your roof, your car, or your neighbor’s fence, have someone who knows what they’re doing prune it properly. A trim in November is a small bill. A branch through your roof in January is a whole different conversation.

Step 3: The Every-Fall Home Maintenance Checklist

This is the stuff I’d do every single year, El Niño or not.

Task	Why it matters	How often
Change the HVAC air filter	The heater runs every night once it’s cold	Every 1 to 3 months (check the box)
Test smoke and CO alarms, swap batteries	California has required CO alarms in single-family homes with gas appliances, a fireplace, or an attached garage since 2011	Every fall
Turn sprinklers down, then off when rain starts	No reason to water during a storm	Every fall
Flush the water heater	Clears sediment so it lasts longer	Once a year, per most manufacturers
Wrap exposed outdoor pipes	Only matters in the hills or spots that get frost	Before the first cold night

If your water heater is near the end of its life, know that the Bay Area’s zero-NOx water heater rule now starts January 1, 2028 and only applies when you replace one. I covered that change in my October 2026 sales recap.

Step 4: Build a Storm Kit for Power Outages

With wet trees and wind, the power is going to go out at some point. Here’s what I’d put together, which is basically what Ready.gov suggests:

• Water, at least a gallon per person per day, for at least three days.
• Food that doesn’t need a fridge or stove, plus a manual can opener.
• Flashlights that work, extra batteries, and a lantern. It beats holding your phone flashlight in your teeth.
• A first aid kit, any prescriptions you need, and food for your pets. My dog Buddy’s food goes in mine.
• Charged phone power banks. A portable power station or a home battery covers a lot more. I worked at Tesla, so I’m a little biased.

If you have a generator instead, it never goes in the garage. Not even with the door open.

How long does food last when the power goes out?

Appliance	How long it holds (door closed)
Refrigerator	About 4 hours
Full freezer	About 48 hours
Half-full freezer	About 24 hours

Keep the doors shut and decide what you want before you open them. Two more quick ones: sign up for PG&E outage alerts so you know if it’s your house or the whole block, and find your water shutoff and electrical panel this weekend. If something starts leaking at 10 at night, you want to know exactly where to go.

Step 5: The This-Year Moves Before El Niño Rain Hits

These are the ones I wouldn’t tell you to do every year. This year, I would.

Check window and door seals

Walk around and look at the caulk around your window frames and the weather stripping on your doors. If it’s cracked or peeling, that’s where wind-driven rain gets in. A tube of caulk is cheap. Drywall repair adds up.

Know your flood risk and get free sandbags

Valley Water has a flood zone lookup and gives out free filled sandbags from November 1 through April 15. If water pools at your garage door in a normal storm, pick them up now and store them on the side of the yard. Don’t wait for the morning of the storm. Lines get long, and sites can run low.

Valley Water sandbag site	Location
San Jose (Central Service Yard)	1661 Senter Road at Phelan Ave
San Jose (Winfield Warehouse)	Winfield Boulevard between Blossom Hill Road and Coleman Avenue
Morgan Hill	171 W Edmundson Ave
Alviso	5030 N 1st St, entrance on Wilson Way
Palo Alto	Palo Alto Air Terminal, 1925 Embarcadero Rd

Sites and dates as listed on Valley Water’s sandbag page in November 2026. Check before you go, since dates can shift with the weather.

Price flood insurance now, because of the 30-day clock

This is the one with the clock on it. Most standard homeowners policies do not cover flooding. A new policy through the federal flood insurance program typically takes about 30 days to kick in. If you wait until the first big storm is on the news, you’re too late for that storm. If you’re near a creek or in a low spot, call your insurance agent this week and get a quote. FloodSmart, the federal program’s site, explains how coverage and cost work.

Insurance is already a bigger part of what homes cost here. I covered the FAIR Plan rate increase and how it splits neighborhoods in the five forces repricing Silicon Valley home values.

How to Prepare Your Home for El Niño: The Full Checklist

Every fall	This year (El Niño)
Clean gutters and extend downspouts	Check window caulk and door weather stripping
Look at the roof from the street	Look up your flood zone with Valley Water
Trim overgrown and dead branches	Pick up free sandbags if water pools near the house
Change filters, test alarms, flush the water heater	Get a flood insurance quote now (30-day wait)
Turn sprinklers down, then off	Build or refresh the storm kit

What I’d Do If I Were Selling in the Spring

A leak you fix in November is a repair. A leak you find in March is a disclosure. When you sell a home in California, the seller disclosure forms ask about flooding, drainage, and grading problems. So if you’re thinking about listing in the spring, this winter is your pre-inspection.

1. Do the five steps above in November, and keep receipts for the roof, tree, and gutter work. Buyers like seeing maintenance on paper.
2. Watch where water goes in the first real storm. Take photos of anything that pools.
3. Fix small leaks right away, while they’re still repairs.
4. If something does happen, disclose it plainly and show the fix. That reads much better to a buyer than a surprise in their inspection.

If you want to avoid the other big mistakes sellers make, read 7 common mistakes home sellers make. And if you’re weighing whether to fix things at all, I covered what selling as-is in San Jose really means.

Frequently Asked Questions

How strong is the 2026 El Niño expected to be?

As of NOAA’s October 8, 2026 update, a strong to very strong El Niño is likely through early 2027. NOAA put the chance that it beats every El Niño on record back to 1950 at 83% for October through December. Strength doesn’t guarantee a wet winter here, so I’d prepare without panicking.

Where can I get free sandbags in Santa Clara County?

Valley Water hands out free filled sandbags from November 1 through April 15 at five sites: Alviso, Morgan Hill, Palo Alto, and two in San Jose on Senter Road and on Winfield Boulevard. Go before the storm, because lines get long and sites can run low.

Does homeowners insurance cover flooding in California?

Most standard homeowners policies do not cover flood damage. Flood coverage is a separate policy, and a new policy through the federal flood program typically has a 30-day waiting period before it starts. Call your agent now, not when the storm is on the news.

How long does food last in the fridge when the power goes out?

About 4 hours if you keep the door closed. A full freezer holds about 48 hours and a half-full one about 24. Keep the doors shut and decide what you want before you open them.

Do I need carbon monoxide alarms in my California home?

If your home has gas appliances, a fireplace, or an attached garage, California has required carbon monoxide alarms in single-family homes since 2011. Test them and your smoke alarms every fall and swap the batteries while you’re up there.

Should I fix storm damage before selling my home in the spring?

Yes. A leak you fix in November is a repair. A leak you find in March is a disclosure, because the California seller disclosure forms ask about flooding and drainage problems. This winter works as your pre-inspection.

Keep Reading

• Silicon Valley Home Values. How insurance and four other forces are repricing the county.
• Cheapest Homes Sold in Santa Clara County. October 2026 sales, plus the water heater rule and Prop 37.
• 7 Common Home Selling Mistakes. What I’d avoid before listing.
• Selling As-Is in San Jose. When skipping repairs makes sense.
• Living in Almaden Valley. The neighborhood I grew up in.

Forecast odds are from NOAA’s October 8, 2026 discussion and sandbag details from Valley Water as of November 2026. This is general information, not legal, insurance, or tax advice. Talk to your insurance agent about your own coverage.