Updated November 2026. Forecast checked November 7 against NOAA's October 8 ENSO discussion, the latest monthly bulletin available; the next is scheduled for November 12.
El Nino vs La Nina in one sentence
El Nino and La Nina are opposite phases of the El Nino Southern Oscillation (ENSO), a natural swing in Pacific Ocean sea-surface temperatures that influences winter weather patterns. During El Nino, the eastern equatorial Pacific runs warmer than average. During La Nina, it runs cooler. Between them is a neutral phase. NOAA's October 8, 2026 ENSO discussion reports a strengthening El Nino, with a greater than 83% chance of strong-to-very strong conditions continuing through January–March 2027.
How each phase changes US winter weather
El Nino winters
- Southern tier of the US: Wetter than normal. The Pacific jet stream shifts south, delivering more atmospheric river storms to California and more Gulf-fed frontal systems to the Southeast.
- California: Southern and Central California most reliably see above-normal precipitation. Northern California is a coin flip.
- Southeast and Florida: Cooler and wetter. Strong El Ninos also produce the specific tornado setup that killed 42 people in Central Florida in February 1998.
- Pacific Northwest: Warmer and drier than normal. The main storm track is displaced south of its usual position.
- Northern tier and Great Lakes: Warmer than average winters, less snowpack.
- Atlantic hurricane season: Quieter. Increased wind shear over the tropical Atlantic tends to shred developing storms.
La Nina winters
- Southern tier of the US: Drier than normal. California, the Desert Southwest, and the Southeast often go into drought.
- Pacific Northwest: Wetter, colder, and snowier than average.
- Northern tier and Great Lakes: Colder than average, more polar vortex intrusions southward.
- Atlantic hurricane season: More active. Reduced wind shear allows more storms to develop and intensify.
Are we in El Nino or La Nina for 2026-27?
El Nino. As checked November 7, the latest monthly NOAA/CPC discussion, issued October 8, 2026, reports:
- A greater than 83% chance of strong-to-very strong El Nino conditions through January–March 2027.
- Historic-strength probabilities of 54% for September–November, 83% for October–December, and 70% for November–January. In this outlook, NOAA defines that threshold as a three-month Relative Oceanic Nino Index (RONI) of at least +2.5°C.
- Observed indices in that bulletin reached +2.1°C in Nino-3.4, +3.0°C in Nino-3 and +3.9°C in Nino-1+2. These are the observations reported in the October bulletin, not a new November measurement.
These are Pacific climate probabilities, not a forecast that a particular home will flood. NOAA emphasizes that typical El Nino impacts become more likely with a strong event but are not guaranteed. Use the regional outlook and local NWS alerts for decisions at home.
What this means for your region
Full regional breakdowns are on the Super El Nino 2026-27 hub. Two deep-dive regional pages are also live:
- El Nino California 2026-27 — atmospheric river timing, burn-scar debris flow risk, county-by-county flood exposure.
- El Nino Florida 2026-27 — winter tornado outbreak setup, the Kissimmee analog, and Gulf-fed storm risk.
For real-time NWS flood alerts by ZIP code, bookmark the StormBag Flood Watch tool.
Why El Nino winters are the higher flood risk (usually)
La Nina winters can produce catastrophic flooding in the Pacific Northwest (November 2021 British Columbia and Washington floods are the classic case). But averaged across the whole country, the number of Americans affected by winter flooding is higher during strong El Nino winters because the Pacific storm track sits over California and the frontal-boundary storm track sits over the Southeast — both of which are densely populated.
El Nino also increases the probability of unusual weather combinations: warm Gulf air fueling tornadoes on the same night that cold Pacific air is dumping snow on the Sierra, cold fronts that stall over the Southeast for days, and coastal storm surge from Nor'easters that get extra energy from a southward-displaced jet.
How to prepare
Review flood insurance well before a storm. Ready.gov's flood guidance notes that NFIP coverage typically takes up to 30 days to take effect. Clear drainage, check alerts and plan evacuation routes before conditions deteriorate.
StormBags weigh about 1 lb dry and expand to about 33 lb in about 3 minutes, absorbing up to 4 gallons of fresh water. StormBag cannot be hydrated in salt water, but will work to repel salt water once hydrated with fresh water. Use the sandbag calculator to plan for your openings, and place barriers before dangerous conditions arrive. Never delay evacuation to protect property.
- Single-Door Kit ($69.99) for a standard 3-foot door
- Double-Door Kit ($109.99) for double doors and sliding patio doors
- Single-Wide Garage Kit ($149.99) and Double-Wide Garage Kit ($239.99) for garages
- 10-Pack or 25-Pack loose boxes for perimeter work
