Bitcoin mining has suddenly become much more difficult. The network increased its mining difficulty by about 15%, pushing it to 144.4 trillion. This is the biggest jump since 2021, and happened after a short slowdown caused by winter storms in the United States.

Mining difficulty is a system that controls how hard it is to create new Bitcoin blocks. The Bitcoin network adjusts this level every two weeks to make sure new blocks are created about every 10 minutes. If more computers are mining, difficulty goes up. If fewer computers are mining, difficulty goes down.

Earlier this month, difficulty actually dropped by about 11%. That was the biggest drop since China banned Bitcoin mining in 2021. The reason was simple: strong winter storms forced many U.S. mining companies to shut down their machines temporarily.

Related: Bitcoin Mining Difficulty Drops 11%, Biggest Cut Since China’s Ban

One of the biggest mining pools, Foundry USA, saw its computing power fall sharply during the storms. Its hashrate dropped about 60%. This showed how much the storms disrupted mining activity.

But the slowdown did not last long. Once power grids stabilized, miners turned their machines back on. The network’s total computing power quickly climbed from 826 EH/s back to above 1 zettahash per second (ZH/s). That is a major level and shows strong participation from miners.

Because the hashrate recovered so quickly, the network automatically raised difficulty again. Developer Mononaut explained it clearly:

In simple terms, the easier period for miners is over.

While higher difficulty makes the network more secure, it also makes life harder for miners. They now need more computing power and more electricity to earn the same rewards.

Meanwhile, mining profits are low. A key measure called “hashprice,” which estimates daily revenue per unit of computing power, is sitting at historic lows of about $28 per petahash per day. That means miners are earning less money for their work than ever before.

Smaller mining companies are feeling the pressure the most. Many already struggle with high electricity costs. When bitcoin’s price is weak, miners often have to sell more of the bitcoin they just mined to pay their bills. This can add selling pressure to the market.

Some analysts are watching the $60,000 bitcoin price level closely. If prices go below that level, weaker miners could be forced to shut down again.

Despite these challenges, large and well-funded mining operations remain strong. Companies and even countries with access to cheap energy continue mining aggressively. Their strength is helping keep the network’s hashrate high.