Seasonal Weather Outlook — Thursday, May 28, 2026

Seasonal Weather Outlook — Thursday, May 28, 2026 El Niño is now 82% likely by next month and trending toward strong event status by autumn, reshaping the summer demand outlook for gas and power across three continents. ENSO & Teleconnections ENSO-neutral conditions technically persist, but the ocean is moving fast. The latest weekly Niño-3.4 index reads +0.4°C, with Niño-1+2 (the easternmost region) already at +1.0°C. More telling: the equatorial subsurface temperature anomaly has increased for six consecutive months, with temperatures exceeding +2°C between 100 and 150 metres depth near the Date Line. The warm water is loaded and ready to surface. The CPC SST consolidation forecast shows Niño-3.4 anomalies reaching +1.5°C (strong El Niño threshold) by September-October-November. A majority of NMME members and the ECMWF model agree. CPC assigns 82% probability of El Niño emerging by May-July 2026 and 96% by December 2026-February 2027. By October-December, there is nearly a two-in-three chance of a strong event. No strength category exceeds 37% individually, so the spread is wide, but the direction is not in doubt. The MJO recently stalled over the Indian Ocean but has resumed eastward propagation toward the Maritime Continent, with dynamical models in good agreement on a robust pulse reaching the Western Hemisphere by early June. This supports near-term tropical convection shifts consistent with early El Niño teleconnections. The NAO sits at +0.42 (neutral) but the GEFS 16-day ensemble shows it drifting toward slightly negative values through mid-forecast before recovering. The AO forecast is more interesting: starting at +0.61 and ramping to +1.89 by day 7, suggesting a strengthening positive AO pattern that would favour mild, westerly flow across NW Europe in the short term. QBO remains easterly at -1.5 m/s (50 hPa), which during El Niño winters historically favours a weaker polar vortex and increased blocking risk for Europe. 6-Week Temperature Trajectory The EC46 ensemble paints a clear picture for NW Europe: warm week 1, sharp cooling week 2, then a gradual recovery. London drops from 18.8°C (week 1) to 15.5°C (week 2, range 13.1-17.9) before recovering to 17.9°C by week 3. Paris follows the same pattern more aggressively: 21.8°C to 17.8°C (range 14.6-21.4) in week 2. The week-2 ensemble spread is wide enough (6.8°C range for Paris) that traders should not commit heavily to the cold solution yet. Frankfurt's trajectory shows week 2 at 17.8°C (range 14.3-21.6), then steady at 20.0-21.0°C through weeks 3-6. The ensemble is widening from week 3 onward, with the week 5-6 range spanning nearly 10°C. Confidence collapses beyond two weeks. Madrid runs hot throughout: 26.1°C week 1 climbing to 28.1°C by week 6 (range 23.6-32.0). The 00Z EC46 changes pushed Madrid even warmer, with July 1 up 2.7°C to 34.9°C. Iberian cooling demand will be structurally elevated through summer. Houston ramps from 25.6°C to 29.8°C over six weeks with tight ensemble spread (2.0-3.5°C ranges), meaning high confidence in sustained US Gulf Coast summer heat. New York's trajectory is the bullish US gas signal: 17.9°C week 1 (cool) jumping to 22.3°C week 2 and building to 24.5°C by week 6. The range widens to 7.7°C by week 6 but the central tendency is clearly upward. Northeast US cooling demand is about to ramp. Regional Seasonal Outlooks The C3S multi-system (incorporating ECMWF, Met Office, Météo-France, DWD, JMA, NCEP, BOM, CMCC, and ECCC) predicts European summer temperatures likely above average across all regions, with the most confident signal over southeastern Europe. Pressure patterns favour anomalously high sea-level pressure over northern Europe, consistent with more settled, warmer conditions. Precipitation signals are weaker, but eastern Europe is flagged for below-average totals in June-August. For the US, CPC's JJA outlook favours above-normal temperatures throughout the West, Great Plains, Lower Mississippi Valley, and East, with highest confidence across the Pacific Northwest. Above-normal precipitation is expected in the Southwest and Northeast. The combination of heat and El Niño-driven moisture patterns points to above-average cooling degree days across most of the CONUS. Mumbai's EC46 shows a monsoon cooling from 30.4°C week 1 to 26.3°C by week 6 with very tight ensemble spread, indicating high confidence in monsoon onset and progression. Seoul and Shanghai both ramp toward summer heat: Seoul from 20.6°C to 24.9°C, Shanghai from 23.6°C to 28.7°C. East Asian cooling demand will build steadily and support JKM through the summer. São Paulo cools through the Southern Hemisphere winter: 15.0°C week 1 falling toward 15.7°C week 6, with ensemble ranges widening to 7.5°C. This is the Brazilian dry season, and below-normal temperatures could support hydro reservoir levels if they coincide with normal rainfall. Strategic Positioning - ICE Endex TTF gas front-month: NW European week-2 cooling (London 15.5°C, Paris 17.8°C) is mildly supportive for gas burn in the 10-14 day window, but the broader summer signal from C3S (above-normal temps, high pressure) is bearish for heating demand. Seasonal TTF should lean lower unless Hormuz supply disruption overwhelms the weather signal. - NYMEX Henry Hub gas front-month and summer strip: El Niño at 82% probability with CPC flagging above-normal temps across most of the CONUS through JJA is unambiguously bullish for US cooling demand. New York EC46 ramps from 17.9°C to 24.5°C over six weeks. Summer Henry Hub should price higher from here. - Platts JKM LNG front-month: East Asian summer heat building (Seoul to 24.9°C, Shanghai to 28.7°C by week 6) supports Asian LNG demand through Q3. El Niño-driven suppressed rainfall around Indonesia could also tighten regional hydro, adding upside. - European power (German baseload, UK day-ahead): Short-term bullish from the week-2 cool spell and lower wind (00Z shifted Frankfurt/Paris June 1 gusts down ~4 km/h). Medium-term bearish from C3S above-normal summer temps and high-pressure pattern reducing gas-for-heating. - Houston/US Gulf Coast summer: EC46 shows 25.6-29.8°C ramp with very tight ensemble spread. High confidence in sustained cooling demand. ERCOT power and Henry Hub summer both supported. - Watch the next El Niño subsurface data (June 11 ENSO discussion): if ocean-atmosphere coupling strengthens through summer as it does in the strongest historical events, the winter 2026-27 implications for European gas demand, Asian LNG, and US heating become much more significant.