The National Atmospheric and Oceanic Administration has said that in the next few days it will stop providing data from satellites that have been helping hurricane forecasters do their jobs for decades, citing “recent service changes” as the cause.

The satellites are jointly operated by NOAA and the Department of Defense as part of the Defense Meteorological Satellite Program. They are old, dating to the early 2000s, but they have reliably helped improve hurricane forecasting for decades. The data will be halted by Monday, June 30, the agency said, without giving further explanation.

“This is an incredibly big hit for hurricane forecasts, and for the tens of millions of Americans who live in hurricane-prone areas,” said Michael Lowry, a hurricane specialist in South Florida who has worked at the National Hurricane Center and the Federal Emergency Management Agency.

The satellites orbit the poles and use microwave radiation to peer inside a hurricane to reveal changes in a storm’s structure. This information is critical for accurately predicting the path of storms and detecting hurricane intensification, particularly at night.

The satellites are not being decommissioned, but their data will no longer be received, processed or stored. Satellites can’t last forever and are eventually retired, but it is not clear that is the case here, said Andy Hazelton, a hurricane modeling expert at the University of Miami. “We don’t want to have less data for no reason,” he said.

NOAA did not respond to a request for comment.

Forecasters rely on various satellite-based tools to monitor tropical cyclones and hurricanes and predict their behavior. Observations of cloud tops and precipitation bands help forecasters see how a storm is moving and spreading. Come nightfall, microwave observation satellites work like forecasters’ night-vision goggles.