Gas market signals and November baseload levels
Central and South-East Europe is entering the December 2025 winter season with day-ahead power prices shaped by a more technically governed market. The winter outlook has shifted away from concerns that previously dominated the region’s planning, including tight gas balances, extreme volatility, supply threats and fragile thermal capacity. Price signals from HUPX in Hungary, OPCOM in Romania, SEEPEX in Serbia and IBEX in Bulgaria point to winter premiums returning without the panic seen in 2022 and the cautious recovery phase of 2023.
The month began after a soft November supported by a benign gas outlook. By Week 48, TTF futures for early 2026 fell below 30 euros per megawatt-hour, reaching an eighteen-month low. That easing fed into regional day-ahead electricity pricing, with November baseload averages clustered around 120 euros across the four markets. Serbia’s SEEPEX cleared at 119.15 euros per megawatt-hour, while Romania’s OPCOM reported a weighted average equivalent of roughly 120–125 euros.
Hungary’s HUPX had already settled into the same price band in October. Bulgaria’s IBEX maintained a mild premium, while its year-to-date average remained around 137 euros. Together, the figures indicate a return to pre-crisis stability across the four exchanges.
Early-December swings on SEEPEX and spillover across zones
The first days of December showed that stability did not eliminate price movement. On SEEPEX, early-month trading produced some of the sharpest intraday swings of the year. Prices started above 150 euros, rose to about 168 euros on a tight day, then dropped below 100 euros by 6 December.
A similar pattern appeared across the region, with different amplitudes between markets. Bulgaria’s IBEX cleared at 125 euros for 5 December, moving closely with SEEPEX and OPCOM levels. HUPX had not published a December average at the time referenced, but its early-December prices tracked the same regional corridor of roughly 110–130 euros.
The timing of these moves highlighted that local conditions can still drive short-lived dislocations even when broader fundamentals are steady. The early-December volatility also came alongside a fuel backdrop that had already eased compared with earlier periods.
Synchronized price formation under SDAC and EUPHEMIA coupling
The regional market structure described for Central and South-East Europe is one where price formation is highly synchronized while volatility remains present. The shift is linked to changes in how day-ahead prices are set across borders rather than to an absence of constraints. Under earlier arrangements, each market reflected different drivers tied to coal-heavy fleets, limited interconnection and state-directed price caps.
The current setup is described as binding the four exchanges into a single pricing basin through Single Day-Ahead Coupling (SDAC) and use of the EUPHEMIA algorithm. Prices move in parallel unless local conditions break the coupling flow. Congestion, hydro variability, temperature swings or thermal outages can still create temporary gaps estimated at 20 to 40 euros per megawatt-hour.
This means spreads can remain tight on most days while still allowing short periods where local fundamentals dominate hourly outcomes. The described mechanism connects market outcomes across Hungary, Romania, Serbia and Bulgaria through shared day-ahead pricing signals.
Q1 2026 scenario ranges for HUPX, OPCOM, SEEPEX and IBEX
The outlook for Q1 2026 is presented through three scenarios built around gas prices, weather conditions and generation availability. For December 2025 specifically, the fundamental setting is described as soft, with cheap gas, stable CO₂ prices and broadly available generation. The winter premium is visible but subdued, and no structural shocks are cited as having emerged.
The base case assumes TTF holds in the 25–35 euro range, hydro conditions remain average and winter temperatures follow standard variability rather than prolonged cold spells. Under those conditions, HUPX, OPCOM and SEEPEX are expected to trade almost indistinguishably within a 115–135 euro band across January through March. Bulgaria’s IBEX is expected to settle slightly higher at roughly 125–145 euros, reflecting chronically higher marginal costs and limited flexibility.
The baseline scenario also includes daily movement estimates ranging from about 90 euros on mild or windy days to around 170 euros on tight days. These spikes are described as flattening out when averaged over each month.
Sensitivity to cold spells and mild-weather outcomes into spring
A second scenario focuses on cold-winter tightening driven by demand increases and reduced hydro output. A severe cold spell in January or February would lift demand sharply and reduce hydro flows, shifting price formation toward CCGTs, lignite plants and imported electricity for most hours of the day. If such weather coincides with gas rising toward about 40 euros per megawatt-hour, day-ahead baseload averages could move into the 150–170 euro band, particularly in Bulgaria and Hungary.
The scenario also highlights Serbia as likely to show stress first due to hydro seasonality challenges and lignite plant outages referenced as common factors. Price risk is then described as spreading outward through coupling when local constraints push prices upward across all four zones. In that stress case, hourly prices above 200 euros per megawatt-hour are described as possible even if monthly averages remain well below crisis-year extremes.
A third scenario covers mild winter conditions where temperatures run above seasonal averages in January and February. It assumes LNG continues flowing into European terminals at the current pace and reservoir levels remain comfortable, limiting pressure on thermal generation. Day-ahead prices could then slide below 110 euros for prolonged periods.
Mild-fundamentals quarter expectations for baseload averaging
If mild weather conditions hold, baseload averages across HUPX, OPCOM and SEEPEX are expected to drift into a 95–115 euro range. IBEX would clear only marginally higher under this scenario. The quarter is described as one of the mildest since full regional coupling was established.
The scenario framework also indicates that plausible outcomes narrow compared with earlier periods when policy or fuel news could drive much wider swings between about 70 euros and 350 euros per megawatt-hour. The December 2025 price curve is described as showing fast swings but modest amplitude relative to those earlier extremes.
The winter period into Q1 2026 is therefore framed around structural fundamentals—fuel levels, weather patterns, interconnection flows and generation availability—rather than abrupt structural shocks cited as absent for December 2025.
Date-specific market references for December 2025 trading points
The described December trading points include SEEPEX clearing above 150 euros per megawatt-hour, reaching about 168 euros, then falling below 100 euros by 6 December. On Bulgaria’s IBEX, clearing at about 125 euros on 5 December is cited alongside tracking close to SEEPEX and OPCOM levels during that period.
The month’s start also references Week 48 TTF futures below 30 euros per megawatt-hour, alongside November baseload clustering near 120 euros. These figures are used as anchors for how day-ahead power pricing moved into early winter across Hungary, Romania, Serbia and Bulgaria.
No additional exchange-specific monthly averages beyond those already stated are provided for HUPX at this stage of December trading in the source material.