Hackers attacked the U.S. weather system in October, causing a disruption in satellite feeds and several pivotal websites.

The National Oceanic and Atmospheric Administration, NOAA, said that four of its websites were hacked in recent weeks. To block the attackers, government officials were forced to shut down some of its services.

This explains why satellite data was mysteriously cut off in October, as well as why the National Ice Center website and others were down for more than a week. During that time, federal officials merely stated a need for "unscheduled maintenance."

Still, NOAA spokesman Scott Smullen insisted that the aftermath of the attack "did not prevent us from delivering forecasts to the public."

Little more is publicly known about the attack, which was first revealed by The Washington Post. It's unclear what damage, if any, was caused by the hack.

Related: Welcome to the Age of Hacks

But hackers managed to penetrate what's considered one of the most vital aspects of the U.S. government. The nation's military, businesses and local governments all rely on nonstop reports from the U.S. weather service.

The impact of the hack was real: Scientists at Atmospheric and Environmental Research in Lexington, Massachusetts were unable to send a preliminary report about weather patterns to traders and investors earlier this year.

"We were shut out entirely. That's our one source of data," said Rutgers climatologist David Robinson, whose global snow lab also relies on the satellite data.

The cyberattack on the U.S. weather system is only the latest one on the United States. The White House was hacked last month. Shortly before that, hackers breached USIS, a federal contractor that knows who has top security clearances for the U.S. government -- because it provides background checks.

Typically, cybersecurity experts blame Russia for hacks on the nation's infrastructure -- or sometimes China.