A major winter storm in the United States recently disrupted more than just daily life. As snow, ice, and freezing rain knocked out power to over one million homes, the storm also forced many Bitcoin miners to shut down. The result was a noticeable slowdown in the Bitcoin network.

Over the past few days, Bitcoin’s total hashrate (the computing power that keeps the network running) dropped by almost 14%. This decline happened at the same time Winter Storm Fern swept across large parts of the Southeast, Northeast, and Midwest.

The biggest impact came from Foundry USA, the largest Bitcoin mining pool in the world. At the height of the storm, Foundry’s hashrate fell by roughly 60%. That meant nearly 200 exahashes per second of mining power went offline.

According to TheMinerMag, “Bitcoin hashrate on Foundry USA alone is down by nearly 200 exahashes per second (EH/s), or 60%, since Friday amid continued curtailment.” The report added that block production temporarily slowed to about 12 minutes.

Bitcoin is designed to produce a new block about every 10 minutes. When a large number of miners suddenly stop working, blocks can take longer to appear. That is exactly what happened during the storm.

At times, average block times stretched to between 11 and 14 minutes. The network continued to function, but transactions are moving more slowly until conditions stabilize in the next difficulty adjustment.

This slowdown highlights a concern researchers have raised for years: mining concentration. When a lot of mining power is grouped in the same regions or pools, local problems can affect the entire network.

A 2021 academic study showed this risk clearly. When a mining-heavy region in China lost power, Bitcoin experienced slower blocks, higher transaction fees, and increased wait times. The same dynamic can happen anywhere mining is concentrated.

Today, mining concentration remains high. The top two mining pools often control more than half of Bitcoin’s total hashrate. The top six regularly produce 80% to 90% of all blocks. Foundry alone usually controls more than 20% of the network.

Because it represents so much U.S.-based mining, changes at Foundry are closely watched. Its performance is often seen as a signal of what U.S. miners are doing overall.

However, not all of the mining shutdowns were caused by power failures. Many miners turned off their machines on purpose.

In the U.S., large Bitcoin miners often act as “interruptible loads.” That means they agree to shut down quickly when the power grid is under stress. Doing so helps redirect electricity to homes, hospitals, and other critical services.

CleanSpark CEO Matthew Schultz confirmed that his company curtailed operations in Tennessee to “push power back to support critical needs.” Similar curtailments happened in regions managed by PJM Interconnection and the Tennessee Valley Authority.

This ability to shut down quickly is often described as a benefit for the power grid. But when many miners do it at once, the Bitcoin network feels the impact immediately. Despite the visible slowdown, bitcoin’s price barely moved during the storm. Mining stocks dipped slightly but did not collapse.

This shows an important point. Short-term drops in hashrate do not always affect price, especially when transaction demand is low. During the storm, transaction fees stayed relatively cheap, limiting the impact on users. Still, analysts warn that the lack of price movement does not mean the issue should be ignored.

On the other hand, the event shows Bitcoin network’s resilience, and how it can keep functioning despite disruptions in physical infrastructure without immediately showing up in the price.

Winter Storm Fern is not a unique event. Similar mining curtailments have happened during heat waves and previous cold snaps, and they are likely to happen again.