As temperatures drop, river-based hydropower output in SE1 and SE2 is being curtailed to prepare stable ice conditions for the winter season.
This annual, weather-driven shift is a familiar feature of Nordic winter operations, but it can still move the market. Reported reductions are reaching up to 3 GW by Friday 21 November, with the expected impact to be felt into next week.
While this mainly hits the northern bidding zones, neighbouring areas such as NO3, NO4 and Finland are also feeling the squeeze, adding pressure across the broader Nordic system.
Recent UMMs highlight the scale of expected limitations:
Lule River (SE1): up to 1.2 GW from 18–20 November and up to 1.8GW from 21–25 November
Skellefte River (SE1): up to 0.3 GW from 21–28 November
Ume River (SE2): up to 0.9 GW from 20–22 November
It remains unclear from the forecasts whether frozen temperatures will continue into next week or if conditions will turn milder.
With winter demand rising and hydropower tightening seasonally, these constraints are set to remain a key price driver for Nordic power system in the days ahead.
