El Niño and Your South OC Home: The Pest Prevention Checklist

Short answer: NOAA expects a strong El Niño this winter, which often (but not always) means a wetter season in Southern California. You don't need to predict the rain to prepare for it. Keeping water moving away from your house, closing small gaps and knowing a few early warning signs will help with ants, rodents and termites in any wet year.

Forecast note (checked October 8, 2026): NOAA's Climate Prediction Center has an El Niño Advisory in effect and says a strong-to-very-strong El Niño is likely through January–March 2027 (greater than an 83% chance). El Niño raises the odds of a wet winter in Southern California, but it does not guarantee heavy rain in South OC. We'll re-check this note before and during the season. NOAA ENSO discussion

Why rain changes pest behavior around a home

Rain doesn't create pests. It changes where they want to be. Saturated soil can push ant colonies to look for drier spots, and some of those spots are inside walls and kitchens. Rodents look for dry, sheltered places to nest. Moisture that sits against wood, stucco or a slab for weeks makes a house more attractive to wood-damaging insects and fungi.

Most of what helps is ordinary home maintenance done a little earlier than usual.

The checklist: before the first big storm

Water: move it away from the house

• Clean gutters and downspouts, and check that water actually leaves the downspout instead of pooling at the foundation.
• Add or reposition downspout extensions so water discharges a few feet from the house.
• Walk the yard after watering and look for low spots that hold water against the foundation.
• Turn irrigation down or off when rain is in the forecast. Wet planters against stucco stay wet a long time.
• Check that slope drains and area drains aren't clogged with leaves or mulch.

Gaps: close the easy doors

• Look at door sweeps on garage and exterior doors. Daylight under a closed door is an invitation.
• Check where pipes, cables and AC lines enter the house. Small openings around them are common entry points.
• Make sure vent screens on the roof, eaves and foundation are intact.
• Store firewood off the ground and away from the house.

Landscaping: trim and clear

• Keep shrubs and groundcover trimmed back from walls so the area stays dry and visible.
• Prune tree branches that touch the roof. UC IPM notes roof rats travel along branches and lines.
• Pull mulch back a few inches from the foundation so you can see the slab edge.

Inside: remove the welcome mat

• Store pantry food and pet food in sealed containers.
• Fix dripping faucets and look under sinks for slow leaks.
• Wipe up crumbs and sticky spots, especially in the kitchen and bathrooms.

During the season: what to watch for

Ants

Lines of small ants coming in along baseboards, around windows or under the dishwasher are common after rain. Clean the trail with soapy water to remove the scent, wipe up the food source and note where they enter. Spraying a few you can see rarely solves the problem, because most of the colony is outside.

Rodents

Droppings in the garage or under sinks, gnaw marks, or scratching in the walls or attic at night are worth taking seriously. Don't sweep or vacuum droppings dry; follow public health cleanup guidance.

Termites

Winged insects swarming near a window, piles of shed wings, small pellet piles, or mud tubes on the foundation are signs to document and ask about. A swarm doesn't automatically mean structural damage, but it's a good reason to get an inspection. See our termite inspection page.

After a storm: a ten-minute walk-around

1. Look for standing water near the foundation and in planters.

2. Check the garage for wet boxes and stored items.

3. Look along baseboards and under sinks for ant trails.

4. Glance at window sills and light fixtures for discarded wings.

5. Take photos of anything unusual, with the date. They help a technician later.

When to call a professional

Call when you see repeated ant invasions despite cleanup, any sign of rodents inside living space, or possible termite evidence. A good technician will identify what's actually there before recommending anything. Treasure Pest offers ant control, rodent control and termite inspections across South Orange County.

How we keep this article current

Forecasts change. We'll update the forecast note above as NOAA updates its outlook, and the date on the note tells you when it was last checked. The prevention checklist stays useful in any wet winter.

Sources: NOAA Climate Prediction Center; UC IPM: Ants; UC IPM: Rats; UC IPM: Drywood Termites.