Seasonal Weather Outlook — Friday, May 29, 2026

Seasonal Weather Outlook — Friday, May 29, 2026 El Nino is building fast toward a strong event by autumn, with 82 percent probability of emergence by May-July and a near two-in-three chance of exceeding the strong threshold by October-December — the dominant seasonal signal for energy markets through year-end. ENSO & Teleconnections ENSO-neutral conditions persist but the transition is underway. The latest weekly Nino 3.4 index sits at +1.2C, well above the +0.4C ONI baseline from March. Subsurface temperature anomalies have increased for six consecutive months with readings exceeding +2C between 100 and 150 metres depth near the Date Line. The NOAA CPC NMME ensemble favours El Nino forming next month and persisting through Northern Hemisphere winter 2026-27 at 96 percent probability. The C3S multi-system seasonal forecast strengthens this further — more than 50 percent of ensemble members now exceed +2.5C Nino 3.4 amplitude by the end of the forecast period. The MJO is in Phase 3 with amplitude 1.6, active and propagating eastward. GEFS dynamical model forecasts agree on a robust MJO reaching the West Pacific and shifting to the Western Hemisphere by early June. The NAO is neutral at +0.42 but GEFS 16-day forecasts show a drift toward slight negative territory through mid-forecast before recovering — consistent with the pattern change delivering cooler NW European temperatures into week 2. The AO shows a positive trend in the GEFS forecast, rising from +0.61 to +1.89 by day 7, which typically supports milder conditions across the mid-latitudes but is being overridden in the near-term by the trough passage. QBO remains easterly at -1.5 m/s at 50 hPa. For energy demand, the El Nino trajectory is the headline. Strong El Nino events historically reduce European winter heating demand by shifting storm tracks south, warm the US Gulf Coast and Southeast through winter, and delay the East Asian monsoon onset. TTF winter 2026-27 and JKM Q1 2027 forward curves should begin pricing the El Nino demand reduction — though the Hormuz supply crisis complicates any straightforward bearish seasonal signal. 6-Week Temperature Trajectory The EC46 ensemble reveals a clear pattern: a near-term warm pulse this weekend followed by a sharp cooldown in week 2 and an uncertain recovery from week 3 onward. NW Europe week 1 runs warm — Paris 19.8C, Frankfurt 18.6C, Amsterdam 17.4C, all above seasonal norms. Week 2 drops sharply: Paris falls to 17.1C with a range of 14.0-20.8C, London to 15.0C with a bottom at 12.7C, Amsterdam to 15.7C. The ensemble spread widens significantly from week 3 onward — Paris week 3 range is 15.5-24.5C, a 9C spread indicating near-zero model confidence in the pattern evolution beyond day 14. The EC46 changes versus yesterday confirm the cooling trend is accelerating. Frankfurt June 2 revised down 4.2C to 22.7C, June 1 down 3.6C to 22.1C. Paris June 2 down 3.0C, June 1 down 2.9C. Amsterdam June 2 down 2.4C. The revisions are uniformly cooler across continental Europe for the day 3-7 window — this is the third consecutive run pushing the NW European week 2 solution colder. The ECMWF IFS 10-day averages tell the same story in different terms: Amsterdam 10-day average 14.2C with week 2 at 12.3C, Paris 10-day 15.3C with week 2 at 11.8C. These are below climatology for early June. Houston week 1 at 26.1C climbs steadily to 29.5C by week 6 — the CDD accumulation curve for ERCOT gas burn steepens through June into July. New York shows a transient week 1 cool spell at 17.2C before rebounding to 22.4C in week 2. Mumbai peaks at 30.5C week 1 then declines through the monsoon onset to 26.4C by week 6. Regional Seasonal Outlooks Europe faces a split signal. The C3S seasonal forecast predicts above-average summer temperatures across all regions, with the highest confidence over southeastern Europe. But the ECMWF also sees anomalously high sea-level pressure in northern regions — a pattern consistent with blocked flow that could produce intermittent cold incursions despite the above-normal seasonal mean. Ensemble anomaly probabilities show 34 percent cold bias for Paris and 26 percent for Frankfurt at day 10. The near-term cooldown does not contradict the seasonal warmth — it is an embedded trough within a generally warm summer pattern. For the US, NOAA CPC's JJA outlook favours above-normal temperatures across the West, Great Plains, Lower Mississippi Valley and East, with highest confidence in the Pacific Northwest. Precipitation tilts above normal for the Southwest, Great Basin and Northeast, below normal along the western Gulf Coast. The developing El Nino reinforces the warm-dry signal for the Southern Plains where ERCOT gas burn is most price-sensitive. East Asia enters the monsoon transition. Tokyo week 1 at 23.7C drops to 20.9C week 2 before recovering. The June 3 wind revision of +7.9 km/h suggests an approaching system. Seoul builds steadily from 20.8C to 25.2C by week 6 — Korean cooling demand ramps through June. Shanghai follows the same trajectory to 28.6C by week 6. The developing El Nino historically delays the East Asian monsoon, which would extend the pre-monsoon heat and associated cooling demand. Sydney's winter deepens — week 1 at 13.7C declining to 11.0C by week 6 with HDD accumulation building for Australian east coast gas demand. Sao Paulo holds steady at 15-16C through the 6-week window — no significant anomaly for Brazilian hydro or agricultural energy demand. Strategic Positioning - ICE Endex TTF week-ahead: firm on NW European cooling into June 2-5. HDD appearing in London and Amsterdam by Thursday signals a brief gas demand uptick that current nominations may not reflect. - TTF winter 2026-27: the El Nino trajectory is structurally bearish for European heating demand, but Hormuz-driven supply constraints dominate. Watch for El Nino pricing to emerge once the geopolitical premium settles. - NYMEX Henry Hub summer strip: NOAA CPC above-normal temps across the South and East support gas-for-power demand. Houston's 6-week trajectory from 26C to 30C confirms ERCOT CDD accumulation. - JKM Q4 2026: El Nino typically warms East Asian autumn, reducing early heating demand. If El Nino reaches strong threshold by October as NOAA projects, JKM Q4 should soften on demand expectations — though Asian LNG supply constraints from Hormuz complicate the picture. - European wind: Amsterdam and London 7-day wind averages of 18 km/h are supportive but not exceptional. The windiest days coincide with the rain and trough passage Tuesday-Thursday — short-lived generation boost, not a sustained wind event. - India monsoon: Mumbai's 6-week cooling from 30.5C to 26.4C confirms monsoon onset progression. MJO propagation into the Maritime Continent by early June supports timely monsoon arrival — bearish for Indian LNG cooling demand but bullish for hydro generation.