Tropical Pacific · official NOAA and IRI data · Canadian airport history
El Niño / La Niña tracker
How to use this page · tap any ? for a full explanation
- The coloured label at the top is NOAA's official El Niño / La Niña status (Watch, Advisory or not active), with NOAA's own summary.
- The tiles give the latest numbers. RONI is the official index: +0.5 °C or more is El Niño, −0.5 °C or less is La Niña.
- Current state shows the ocean (weekly Niño values) and the atmosphere (SOI). A real event needs both to agree.
- Strength tracker compares the current event with 1997–98, 2015–16 and other famous events.
- Outlooks show where forecasters and about two dozen models expect it to go over the next few seasons.
- Canada shows what El Niño and La Niña winters have meant at Canadian airports: a tilt in the odds for the season, not a day-to-day forecast.
New here? Start with what ENSO is and the official status, then what it means for Canada. Words are explained in the glossary at the bottom.
Everything here is republished from NOAA CPC, NOAA NCEI and IRI (Columbia University) with the source and date shown, or computed from official data as described under Sources and methods. MeteoFrontier makes no ENSO forecast of its own; this page is not an official forecast.
Current state
Weekly Niño-region SST anomalies
NOAA CPC weekly OISST, 1991–2020 base.
Southern Oscillation Index (atmosphere)
Standardized Tahiti minus Darwin sea-level pressure, monthly (NOAA CPC). Sustained negative values (weaker trade winds) go with El Niño, positive with La Niña.
Oceanic Niño Index history, 1950 to now
How to read it. Each value is a 3-month running mean of the Niño-3.4 SST anomaly (5°N–5°S, 170°–120°W; ERSSTv6, centred 30-year base periods). CPC calls El Niño (La Niña) conditions when the index is at or above +0.5 °C (at or below −0.5 °C); a historical episode needs 5 overlapping seasons in a row. Strength categories used here are the common convention, also used in CPC's strength outlook: weak 0.5–0.9, moderate 1.0–1.4, strong 1.5–1.9, very strong ≥ 2.0 °C. RONI (relative ONI) subtracts the tropical-mean (20°N–20°S) SST anomaly and rescales, so a warming ocean everywhere does not count as El Niño; since NWS statement 26-05 CPC uses RONI for official ENSO monitoring and prediction (van Oldenborgh et al. 2021). The traditional ONI is shown for comparison with older records.
Strength tracker
Where the current state sits
Latest values on the conventional strength scale. RONI and ONI are 3-month means; the weekly Niño-3.4 value is a single week and runs ahead of them.
Peak strength of past events
The current event against famous ones
3-month index from January of the onset year to December of the next year.
Ocean maps
Tropical Pacific sea-surface temperature anomaly
Equatorial SST, time vs longitude (Hovmöller)
How warm and cool water has moved along the equator over the past year. Eastward-sloping warm streaks are typically downwelling Kelvin waves.
Below the surface: equatorial temperature anomaly
Depth vs longitude, 0–450 m, 2°S–2°N (NOAA CPC GODAS). The heat stored here feeds or ends an event months ahead of the surface.
Global SST anomaly, latest month
The ENSO pattern in context: the tropical Pacific next to the North Pacific, where the Pacific Decadal Oscillation and marine heatwaves also shape western Canadian winters.
Outlooks (official and model)
These are the forecasters' and models' outlooks as published, attributed to their issuers. MeteoFrontier does not alter or blend them.
NOAA CPC official ENSO probabilities
NOAA CPC official RONI outlook
NOAA CPC official strength probabilities
IRI ENSO prediction plume: Niño-3.4 forecasts from the models
Model values (table)
The IRI plume uses the traditional (not relative) Niño-3.4 index, so its values run higher than CPC's RONI outlook in a warm tropical ocean. Model skill differs and falls with lead time, and forecasts made in northern spring are the least reliable. CMC CANSIP is Environment and Climate Change Canada's CanSIPS system. ECCC's own seasonal outlooks for Canada are at weather.gc.ca/saisons.
What it has meant for Canada
The established pattern
ENSO reaches Canada mainly in winter, through the Pacific–North American pattern and a shift in the Pacific jet stream. Peer-reviewed analyses of Canadian station records found:
- El Niño winters tend to be milder than normal across western and central Canada (British Columbia through the Prairies into northwestern Ontario), with the strongest warm signal over the west and the Prairies (Shabbar and Khandekar 1996), and drier than normal over much of southern Canada, especially from British Columbia across the Prairies and the Great Lakes (Shabbar, Bonsal and Khandekar 1997). The storm track tends to shift south of Canada (NOAA CPC; Ropelewski and Halpert 1986).
- La Niña winters tend toward the opposite: colder than normal in western and central Canada, and wetter than normal over much of the same region, where winter precipitation falls largely as snow (Shabbar and Khandekar 1996; Shabbar et al. 1997).
- The signal is strongest in December to March and weak in summer. Atlantic Canada and the eastern Arctic show weaker and less consistent links.
- ENSO shifts the odds; it does not decide a winter. Other modes (the PDO, the Arctic Oscillation, the MJO) and plain weather noise matter, and no two events produce the same winter. Even a very strong event does not guarantee the typical impacts (NOAA CPC).
Our evidence: winters at MeteoFrontier airports by ENSO phase
By region
By airport
Sources and methods
References
- Mantua, N. J., S. R. Hare, Y. Zhang, J. M. Wallace and R. C. Francis, 1997: A Pacific interdecadal climate oscillation with impacts on salmon production. Bull. Amer. Meteor. Soc., 78, 1069–1079. doi
- Ropelewski, C. F. and M. S. Halpert, 1986: North American precipitation and temperature patterns associated with the El Niño/Southern Oscillation (ENSO). Mon. Wea. Rev., 114, 2352–2362. doi
- Shabbar, A. and M. Khandekar, 1996: The impact of El Niño–Southern Oscillation on the temperature field over Canada. Atmosphere-Ocean, 34(2), 401–416. doi
- Shabbar, A., B. Bonsal and M. Khandekar, 1997: Canadian precipitation patterns associated with the Southern Oscillation. J. Climate, 10, 3016–3027. doi
- van Oldenborgh, G. J., H. Hendon, T. Stockdale, M. L'Heureux, E. Coughlan de Perez, R. Singh and M. van Aalst, 2021: Defining El Niño indices in a warming climate. Environ. Res. Lett., 16, 044003. doi
- NOAA CPC: ENSO and North American winter; NOAA Climate.gov ENSO blog.
IRI plume data: ENSO Forecast Data © 2002–2026 by International Research Institute for Climate and Society is licensed under Creative Commons Attribution 4.0 International; values read from IRI's published plume figure and redrawn. NOAA data are US Government works, free to use with attribution. Maps drawn by MeteoFrontier from the named NOAA data.
Glossary: words used on this page
See the site glossary.