El Nino vs La Nina in one sentence
El Nino and La Nina are the two opposite phases of the El Nino Southern Oscillation (ENSO), a natural swing in Pacific Ocean sea-surface temperatures that drives the world's 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. For the 2026-27 winter, NOAA has assigned a greater than 90% probability of a very strong El Nino, with a 69% chance the event will surpass every El Nino on record since 1950.
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. The current forecast is not close.
- NOAA's Climate Prediction Center puts the probability of at least a very strong El Nino at greater than 90% for the Northern Hemisphere fall and winter 2026-27.
- The probability that this event will surpass every El Nino on record since 1950 is 69%.
- The forecast peak in the Nino 3.4 sea-surface-temperature anomaly is just under +2.5 degrees Celsius during October-November-December, with observed eastern equatorial Pacific anomalies already exceeding +3.0 degrees Celsius.
- The informal threshold for a "Super El Nino" is Nino 3.4 anomalies exceeding +2.0 degrees Celsius. The 2026-27 event is on track to clear that comfortably.
The closest historical analogs are the 1997-98 and 2015-16 El Nino winters, both of which produced record precipitation in parts of California and unusually severe winter weather across the Southeast. NOAA also compares the current setup to the 2024 winter, which was among the wettest Februaries in the last 100 years for parts of California.
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
The 30-day NFIP waiting period means the time to buy flood insurance for the 2026-27 winter is now, not November. For last-mile physical containment when the forecast turns bad, StormBags stack flat in a closet or garage and hydrate in about five minutes on fresh water contact. Each bag absorbs 4.5 gallons. Use the sandbag calculator to size for your specific openings.
- 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
