Bitcoin block time slows as sweeping US winter storm strains power grid, prompting miner curtailments

A sweeping U.S. winter storm has forced a sharp pullback in bitcoin mining activity, knocking a significant share of the network’s computing power offline as operators curtail electricity use to ease pressure on strained power grids.

The storm, named Fernan, has driven extreme cold, snow, and ice across large parts of the country, leaving more than one million residents without power and prompting grid operators to issue conservation alerts.

During the extreme weather, Foundry USA — the largest bitcoin mining pool by hashrate — has seen its connected computing power drop by roughly 60% since Friday. Data from miningpoolstats.stream shows Foundry USA’s hashrate falling from a recent peak near 328 exahashes per second (EH/s) to about 139 EH/s. Foundry currently accounts for roughly 23% of the global mining pool hashrate market share, according to The Block’s data.

Hashrate refers to the amount of computing power dedicated to securing the Bitcoin network and processing transactions. When large amounts of hashrate drop offline, blocks are produced more slowly until the network’s automated difficulty adjustment rebalances mining incentives.

In total, an estimated 200 EH/s has gone offline across the network, pushing average bitcoin block times above the protocol’s 10-minute target. Mempool data shows average block times climbing to roughly 12.4 minutes, with the next bitcoin difficulty adjustment currently estimated at a 15% downward reset — a mechanism designed to restore block production cadence after sustained hashrate declines.

Other U.S.-focused pools have also been affected. Luxor, another major North American mining pool, saw its hashrate fall from roughly 45 EH/s to around 26 EH/s over the same period. Smaller declines have also been observed at Antpool and Binance Pool, suggesting total curtailments may exceed 110 EH/s, even though those pools are less concentrated in the U.S.

Flexible bitcoin power needs

The pullback reflects a growing pattern in which bitcoin miners act as flexible, interruptible loads during periods of extreme weather.

Many large-scale mining operations participate in demand-response programs, allowing them to rapidly shut down rigs, sell power back to the grid, or avoid operating during peak pricing periods — receiving compensation or energy credits for doing so — in order to stabilize the electricity system.

The Block has documented similar episodes in past weather-driven disruptions. In early 2024, bitcoin mining hashrate fell by an estimated 25% during large-scale curtailments in Texas as miners powered down to relieve grid stress. More recently, a bout of extreme cold in the U.S. contributed to Bitcoin’s first negative difficulty adjustment in four months, underscoring how weather shocks can temporarily reshape network conditions.

The contrast with earlier grid crises is notable. During Texas’s February 2021 Winter Storm Uri, large-scale crypto mining was far less integrated into grid management. Since then, Texas and other U.S. regions have added substantial large-load capacity, much of it tied to bitcoin mining and data center operations designed to ramp consumption up or down quickly.

For the Bitcoin network, the slowdown remains mechanical rather than structural. Once weather conditions ease and miners reconnect equipment, hashrate is expected to rebound, restoring block times and reinforcing miners’ role as both industrial consumers and shock absorbers during periods of grid stress.

It’s important to note that this flexible-load model may face limits over time as portions of the mining sector increasingly diversify into artificial intelligence and high-performance computing. Unlike bitcoin mining, those workloads are often less tolerant of sudden curtailment, potentially altering how future data centers interact with power markets during periods of stress.

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