Seasonal Weather Outlook, Wednesday June 24, 2026
A major El Niño is now building in the Pacific, with a 63% probability of ranking among the strongest events on record by November-January, the dominant signal shaping energy demand across every hemisphere through late 2026 and into early 2027.
ENSO and Teleconnections
El Niño conditions have arrived. The weekly Niño-3.4 index stood at +1.9°C as of June 17, with the eastern Niño-1+2 index at +2.1°C, well past the El Niño threshold. Critically, the equatorial subsurface remains loaded with anomalously warm water through depths of 200 metres, providing the oceanic fuel for continued intensification. The C3S June forecast, combining ECMWF, Met Office, Météo-France, DWD, CMCC, NCEP, JMA, ECCC, and BOM, shows 75% of grand-ensemble members exceeding 2.5°C Niño-3.4 amplitude by November. The NMME multi-model mean reaches +2.0°C in October-November-December. CPC puts the peak median at +1.9°C in the November-December-January season. NOAA's probability assessment gives a 63% chance of a very strong event during that window, one that would rank in the top tier of the historical record since 1950.
The atmospheric coupling is progressing on schedule. Low-level westerly wind anomalies are expanding across the central equatorial Pacific, upper-level easterly anomalies have set in, and the Southern Oscillation Index is negative. Convection is running above average near the Date Line, suppressed over Indonesia. The positive feedback loop is turning.
The MJO is active at Phase 7, amplitude 1.6. Phase 7 propagation places enhanced convection near the dateline and western Pacific, consistent with the developing El Niño pattern and typically supportive of continued atmospheric coupling. The QBO remains in an easterly phase (-1.5 m/s at 50 hPa), which in a strengthening El Niño winter tends to produce a weaker and more disturbed polar vortex, raising the probability of stratospheric warming events and cold outbreaks to Europe and North America in Q1 2027.
Near-term teleconnections are relatively contained. The NAO is neutral (-0.31) and the GEFS 16-day ensemble keeps it near zero, with no strong blocking signal developing into early July. The AO is slightly positive (+0.30) and the GEFS shows a strengthening trend through the forecast window, reaching +1.89 by day eight, suggesting a more zonal Arctic pattern through mid-July, which keeps cold air locked at high latitudes and supports continued summer warmth across temperate Europe and North America. The PNA is negative (-0.68), reflecting the ridge-over-the-Pacific pattern characteristic of early El Niño episodes.
Six-Week Temperature Trajectory
The EC46 extended ensemble shows a striking pattern for northwestern Europe: week one is hot, week two breaks sharply, and weeks three through six settle into a warmer-than-normal but not exceptional range. London runs at 23.2°C in week one, dropping to 18.9°C in week two, a departure driven by the recent cold plume visible in yesterday's run-to-run changes, which shifted London and Amsterdam down by 3–4°C for late June and early July. Frankfurt follows the same structure: 27.8°C in week one collapsing to 20.6°C in week two, with the ensemble spread widening substantially (16.9–24.3°C range), reflecting genuine uncertainty about how long the cooler Atlantic air mass lingers. From week three onward, Frankfurt stabilises in the low 20s, and the warm-tail probability is substantial: the ECMWF ensemble shows Frankfurt's warm-1.5-standard-deviation probability averaging 38.2% across the forecast window, warm-2-standard-deviation at 27.5%, statistically skewed toward above-normal for the summer as a whole.
Madrid sits in a different regime entirely. The Iberian peninsula shows persistent warmth from week one through week six (28.5°C down to 27.0°C and back to 28.9°C), with very little ensemble spread. Southern Europe is in high-confidence above-normal territory through at least mid-August. Houston confirms El Niño's US footprint: a steady warming from 28.2°C in week one to 30.0°C by week six, with the ensemble consistently skewed warm and spread narrowing with each passing week, confidence above normal through July and August is high.
Japan warms seasonally across all three cities (Nagoya, Osaka, Tokyo region), moving from 21°C into the upper 26–27°C range by weeks three and four. The pattern fits El Niño's typical fingerprint, a warmer-than-normal pre-Obon period, though the ensemble spread is moderate (2–3°C at each point), leaving JKM demand projections with real uncertainty either side.
Regional Seasonal Outlooks
For Europe, NOAA CPC and the C3S multi-model ensemble agree on the broad summer: above-normal temperatures likely through JAS 2026, with the highest confidence in southern and central Europe. DWD's seasonal outlook for Germany is near-normal to above-normal through August, somewhat less bullish than the ECMWF, which has the warm tail probability dominating, but the direction of travel is consistent across agencies. Where agencies diverge is on duration: ECMWF sees the warm anomaly persisting into autumn, while Met Office and Météo-France seasonal products are more cautious about September, given that El Niño's European teleconnection is relatively weak in summer compared to winter.
In East Asia, JMA's 3-month forecast is unavailable in detail here but the broader context is consistent: El Niño summers in Japan and Korea are characterised by below-normal typhoon activity over mainland areas but elevated Pacific typhoon formation, and near-normal to slightly above-normal temperatures over the Korean Peninsula through September. China faces a heterogeneous pattern, above-normal summer temperatures in the north, with the monsoon progression being the key variable for both power demand and hydro generation.
The Indian monsoon deserves specific attention. El Niño events of this magnitude are historically associated with below-normal monsoon rainfall, NOAA's seasonal guidance notes the suppressed convection over Indonesia and the Maritime Continent, which typically reduces moisture flux into the Indian subcontinent. IMD's operational forecast has shown caution, though a final call is not yet available. If the El Niño intensifies on the current trajectory, kharif agricultural output and hydro-reservoir levels across the Deccan plateau face meaningful downside risk through the August-September period.
In the Americas, CPC's JAS outlook is direct: above-normal temperatures are likely across the Pacific Northwest, the southeastern United States, and New England, with the highest probabilities along the East Coast. Below-normal precipitation is favoured for the Southern Plains and Lower Mississippi Valley, a headwind for crop-cooling water availability and a support for natural gas power burn. Brazil's hydropower story is more nuanced: Sao Paulo shows a slight warming correction in the EC46 run (up 2.4°C by early August versus yesterday's forecast), but the austral winter season limits immediate hydro concerns. The Pacific La Niña residual influence on Southern Brazil precipitation has faded, and the current El Niño pattern is typically drier for the northeast while the south sees near-normal rainfall.
Hydro and Storage
EU gas storage is not in distress at current summer fill rates, but the seasonal trajectory matters more than the snapshot. An El Niño autumn in Europe tends to run warmer and slower-demand than climatological norms, which supports injection pace. However, the QBO-easterly interaction in winter raises the risk of sudden stratospheric warming events in Q1 2027, which can deliver sharp cold snaps even in otherwise mild El Niño winters. Nordic hydro reservoir levels are tracking near seasonal averages following a wet spring in Scandinavia, Oslo's EC46 ensemble shows temperatures near 16–19°C through the six-week window, consistent with normal summer conditions and no extraordinary melt stress.
Strategic Positioning
- European Q3 power and gas: The week-two cool break in NW Europe reduces near-term cooling demand risk, but the multi-week warm bias in southern Europe (Spain, Italy) supports Iberian power demand and EUA clearing. TTF Summer-26 remains sensitive to any prolonged sub-seasonal cool anomaly in weeks three through six, currently not the base case.
- European Q4 and Winter 26-27 gas: The QBO-easterly phase and strengthening El Niño increase the probability of at least one cold spell disrupting the otherwise mild El Niño winter pattern. Storage fill at 70%+ going into October limits upside, but Cal-27 strip is underpricing polar vortex disruption risk given the atmospheric setup.
- US natural gas, Henry Hub Aug-Sep: The CPC JAS outlook for above-normal temperatures across the South and East, combined with Houston's steady warming trajectory to 30°C by week six, supports elevated power-sector gas burn through the summer. Near-term below-normal precipitation in the Southern Plains amplifies the demand signal.
- JKM Q3: Japan's warm trajectory into weeks three-four, combined with El Niño's typical suppression of Pacific typhoon landfalls reducing hydro reservoir replenishment risk, keeps LNG demand from Japan elevated through August. The spread in the ensemble (±2°C) leaves room for cooling demand to disappoint, but the risk is skewed upward.
- India LNG and coal: Below-normal monsoon probability rising under this El Niño configuration is a medium-term bullish signal for LNG imports and coal burn if hydro generation disappoints in August-September. Watch July actual monsoon deficits as the leading indicator.
- Brazilian hydro and Latin American gas: Current austral winter conditions are benign, but a developing El Niño historically reduces late-wet-season rainfall in northeast Brazil (January-March 2027). Early positioning in Brazilian power curves for Q1 2027 is warranted once wet season forecasts begin firming in September.