What Is El Niño? A Breakdown Guide for Homeowners and Their Properties Storm Preparation & Recovery Submitted by Elisa Edelstein Reviewed by Expert Erik Lindberg, Assistant Plant Care Director Key Takeaways: El Niño is the warm phase of the El Niño-Southern Oscillation (ENSO), a natural climate cycle in which weakened trade winds let warm water spread east across the tropical Pacific, shifting the jet stream and U.S. winter weather. El Niño returns every two to seven years, typically lasts nine to 12 months, and peaks between November and February, so its effects in the U.S. are strongest in winter. As of October 2026, NOAA gives a greater than 83% chance that a strong-to-very-strong El Niño will continue through January to March 2027. The southern U.S., from California to the Carolinas, tends to have a wetter, cooler, and stormier El Niño winter, while the northern tier tends to be warmer and drier. In wet regions, saturated soil raises the risk of Phytophthora root and crown rot and makes trees more likely to uproot when high winds follow heavy rain. In dry, mild regions, low snow cover can injure tree roots during dormancy, and the damage often doesn’t appear until spring or summer. Warm-season lawns in the wetter South face a higher risk of large patch disease, while lawns in drier regions are more prone to winter damage when snow cover is low. Homeowners in wet-winter regions should improve drainage and cut back irrigation, while those in dry-winter regions should water trees and shrubs once or twice a month during dry spells when temperatures are above 40°F. SavATree’s ISA Certified Arborists can evaluate large or mature trees near homes for structural and root problems before winter storms arrive. El Niño is a natural climate pattern that begins when water in the tropical Pacific Ocean warms above average temperatures. That warm water disrupts wind and storm patterns worldwide, which can bring a wetter, warmer, drier, or cooler winter than usual to your area. As of its October 2026 update, NOAA’s Climate Prediction Center reports that El Niño is still strengthening and that a strong-to-very-strong event is likely through early 2027. For homeowners, that can mean significant changes in how much rain, cold, and snow your trees and landscape face over the next several months. This guide explains El Niño in simple terms, shows which parts of the U.S. it tends to affect, and covers what it may mean for landscapes in each region. What Is El Niño? El Niño is the warm phase of a natural climate cycle in the tropical Pacific Ocean called the El Niño-Southern Oscillation, or ENSO (pronounced “en-so”). During El Niño, the winds that normally blow from east to west across the tropical Pacific weaken. Warm surface water then spreads east, and ocean temperatures in the central and eastern Pacific climb above average. That warmer water shifts where storms form over the Pacific. Those shifts move the jet stream, the high-altitude river of air that steers weather across North America. When the jet stream moves, so do the usual paths of rain, snow, and cold air. NOAA offers a helpful way to picture it. El Niño is not a storm that “strikes” a place. It works like a big construction project across town that reroutes traffic. You feel it through changes to normal patterns, even though nothing lands on your house. ENSO has three phases: El Niño is the warm phase, when the tropical Pacific runs warmer than average. La Niña is the cool phase, when the tropical Pacific runs cooler than average. Its effects are roughly the opposite of El Niño’s. ENSO-neutral is the in-between state, when ocean temperatures, winds, and rainfall are close to their long-term averages. The name dates back centuries. South American fishermen noticed warm coastal water and smaller catches around Christmas and named the pattern after the Christ child. Scientists later named the cool phase La Niña, Spanish for “little girl”. How often does El Niño happen, and how long does it last? El Niño returns every 2 to 7 years on average and usually lasts nine to 12 months. It is an irregular cycle and has no fixed schedule. Most events follow a similar rhythm. El Niño tends to form in spring, reach peak strength between November and February, and fade the following spring or early summer. That is why its effects in the U.S. are strongest in winter and can linger into early spring. El Niño rarely endures much more than a year. The longest one in the modern record ran 18 months. A strong El Niño is often, but not always, followed by La Niña the next year. How do scientists track El Niño? In the U.S., NOAA’s Climate Prediction Center tracks El Niño and posts an official update every month. Scientists watch ocean temperatures in a stretch of the equatorial Pacific called the Niño-3.4 region, using satellites, weather balloons, and ocean buoys. Two things must happen before NOAA says El Niño conditions are present. The ocean in that region must be at least 0.5°C (about 0.9°F) warmer than average, and the atmosphere above it must start behaving as it does during El Niño, with shifts in wind, air pressure, and rainfall. The larger the temperature increase, the stronger the El Niño. Scientists describe events as weak, moderate, strong, or very strong. A stronger event raises the odds of typical El Niño weather, but it does not guarantee it. NOAA notes that typical El Niño impacts in the U.S. may occur as often as 80% of the time or as rarely as 40%, depending on the place, which can affect your property and how it responds What parts of the U.S. does El Niño affect? El Niño affects most of the U.S. in two general ways. Because of the jet streams, the southern half of the country tends to get a cooler, wetter, stormier winter, while the northern half tends to get a drier and milder winter. During El Niño, it tends to dip south and stretch west to east across the southern states, steering more storms from California to the Carolinas and leaving the northern tier with fewer. Here is the typical El Niño winter pattern in simple terms: Southern tier (California, the Southwest, Texas, the Gulf Coast, Florida and the Carolinas) tends to be wetter and cooler than average, with a higher chance of severe winter weather. Pacific Northwest, northern Rockies, and Alaska tend to be warmer and drier than average. Upper Midwest and Great Lakes tend to be warmer than average. Northeast and Mid-Atlantic have a weaker, less predictable signal that may swing either way. Outside of the winter months, El Niño tends to reduce Atlantic hurricanes and increase hurricanes in the eastern and central Pacific. How El Niño may affect landscapes by region For trees and shrubs, El Niño mostly comes down to two risks. Prolonged soil saturation can deprive roots of oxygen, damaging the root system and increasing susceptibility to root diseases such as Phytophthora. Compromised root systems may also reduce tree stability, particularly during periods of high winds. Conversely, too little water during a dry, mild winter season can damage roots, and the tree may not show physical symptoms of stress until spring or summer. California and the Southwest This region tends to get wetter during El Niño winters. After a dry stretch, that rain is welcome, but NOAA warns that heavy rain on dry ground can cause flash floods and mudslides. The soggy soil may increase disease risk. University of California researchers note that almost all fruit and nut trees and most ornamental trees and shrubs can develop Phytophthora root and crown rot when soil around the plant stays wet for long periods. Young trees are the most vulnerable, and infected plants often wilt and decline once warm weather returns. Texas, the Gulf Coast and the Southeast The southern states tend to see a stormier El Niño winter as the jet stream tracks across the region. That raises the chance of winter severe weather, including strong winds. Wet soil and wind are a risky pair for trees. University of Georgia Extension explains that uprooting is common when high winds follow heavy rain, because saturated soil softens and trees can topple, roots and all. Trees with shallow roots, past root damage, or internal decay face the greatest risk. Mid-Atlantic and Northeast This winter, NOAA’s outlook leans toward a warmer and wetter season along much of the East Coast. Repeated soaking rains combined with coastal storms bring the same root and wind concerns seen farther south. Midwest and Great Lakes These states tend to have a milder El Niño winter. NOAA’s current outlook favors warmer-than-average temperatures across the Midwest and drier-than-average conditions in some parts of the Great Lakes. A milder winter with less snow cover can leave soil drier than trees need heading into spring. Pacific Northwest and Northern Rockies El Niño winters here tend to be warmer and drier, with less snow. For 2026-27, NOAA expects that drought will develop or worsen across parts of the northern Rockies, northeastern Oregon and eastern Washington. Dry winters can harm trees even while they are dormant. Colorado State University Extension notes that long, dry fall and winter periods can injure or kill parts of a plant’s root system. Damaged plants may leaf out normally, then weaken or die later in the season. Colorado Front Range and the Intermountain West This region sits between El Niño’s wet South and dry North, so the signal is mixed. NOAA gives much of the Intermountain West equal chances of a wetter, drier, or near-normal winter. The Front Range’s usual winter challenges such as dry air, little snow cover, and swinging temperatures are still likely, and newly planted trees, evergreens, and shallow-rooted trees like birch, linden, and many maples are most at risk from winter drought. What happens to lawns during El Niño Lawns face their own version of El Niño’s wet-or-dry split. In the wetter South, the bigger concern is disease. University of Florida researchers note that large patch, a common disease of warm-season grasses like St. Augustinegrass and zoysiagrass, most often appears from November through May when temperatures stay below 80°F. Rain, overwatering, or long humid spells that keep grass blades wet for 48 hours or more can trigger it. A large patch usually starts as yellowing circles about a foot across that turn brown and can spread to several feet wide. Because it strikes when warm-season grass is growing slowly, recovery can take a while. In milder, drier regions, the risk flips to winter dryness. Colorado State University Extension notes that lawns are prone to winter damage when snow cover is low. Newly seeded or sodded lawns, and lawns with south or west exposure, are most vulnerable. Tracking El Niño 2026-27: An updated guide Last updated October 26, 2026. This section is refreshed as NOAA releases new data. El Niño is active and still strengthening. NOAA has an El Niño Advisory in effect, and its October 8 update gives a greater than 83% chance that a strong to very strong El Niño continues through January to March 2027. Ocean temperatures in parts of the eastern tropical Pacific ran more than 4°C (about 7°F) above average in September. NOAA estimates an 83% chance that, during October to December, this El Niño will be stronger than any on record going back to 1950. NOAA’s winter outlook for December 2026 through February 2027 follows the classic El Niño pattern: warmer across the North, and wetter across the southern tier and up the East Coast. Hot spot What NOAA expects this winter What to watch in the landscape Southwest and Southern California Wetter than average; drought likely to improve Runoff on dry slopes, erosion, root and crown rot in poorly drained soil Southern Great Plains and Texas Wetter than average; drought likely to improve Saturated soil around shallow-rooted trees, uprooting during wind events Southeast and Florida Wetter than average; near-normal temperatures Storm and wind damage, waterlogged root zones, large patch in warm-season lawns East Coast Wetter and warmer than average Repeated soaking rains, limb and root failures in coastal storms Midwest and Mississippi Valley Warmer than average Low snow cover and dry soil heading into spring Northern Rockies, eastern Washington and northeastern Oregon Drier than average; drought likely to develop or worsen Winter drought injury, especially in young trees and evergreens Source for the outlook columns: NOAA 2026-27 U.S. Winter Outlook. How to prepare your landscape for El Niño The best preparation is dependent on whether your area is more likely to get a wet winter or a dry one. A few simple steps now can help your trees and shrubs stay healthy through the season. If your winter is likely to be wetter than normal Look for spots where water pools after rain. University of California experts say the most important way to prevent root and crown rot is to avoid long periods of soggy soil or standing water around the base of trees Point sprinklers and drip lines away from tree trunks, and keep mulch from piling up against the base of a tree Reduce irrigation during rainy stretches and water only when the soil needs it After storms, watch for a new lean, cracked, or raised soil near the base of a tree, or mushrooms on the trunk or root flare. These can signal root problems or decay For warm-season lawns, water only when needed and in the early morning, avoid heavy nitrogen feeding during cool, wet weather, and mow any patchy areas last so the mower doesn’t spread disease If your winter is likely to be milder and drier than normal Water trees and shrubs during extended dry periods without snow cover, about once or twice a month, as Colorado State University Extension recommends Water only when air and soil temperatures are above 40°F, and water at midday so it can soak in before night Give young trees extra attention, since newly planted trees are the most likely to suffer winter drought injury. A common guideline is about 10 gallons of water per inch of trunk diameter per watering Add a layer of mulch to help hold soil moisture through dry weather, keeping it a few inches off the trunk Water lawns during long dry spells, paying closest attention to new lawns and lawns facing south or west. Windy spots and areas that catch reflected heat from walls or fences dry out faster and need extra water Get a professional opinion on large or older trees Big, mature trees near homes, driveways, and walkways deserve a closer look before winter storms arrive. SavATree’s ISA Certified Arborists can evaluate tree structure, visible signs of root problems, soil conditions, and other environmental stress factors that may be impacting the property. From there, they may recommend pruning or other appropriate care for your property. Contact us today to schedule a consultation with an expert arborist.