Calm weather and a lack of storms are generally considered good news entering the holiday season, but in Europe, a lack of seasonal wind is wreaking havoc on energy markets. Falling wind speeds experienced all across Europe are pushing power and gas prices higher, underscoring the heightened vulnerability of the continent’s energy system to weather conditions this winter. Amid a sharp pivot from its reliance on Russian natural gas, Europe has built up large reserves of stored gas ahead of this year’s heating season. That has helped ease power and gas prices recently and a particularly mild spell of weather across the continent also helped by pushing back gas withdrawals and keeping stockpiles topped off. Now, though, colder weather in many places is kicking in at the same time wind speeds have fallen, bolstering demand for gas while reducing the ability of wind farms to generate electricity. With temperatures dropping, this winter is shaping up to be a costly one for customers’ wallets.