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About 600 miles , large clusters of thunderstorms begin organizing into tropical storms every hurricane season. They aren't yet in range of , so forecasters at the rely on weather satellites to peer down on these storms and beam back information about their location, structure and intensity.

The satellite data helps meteorologists create weather forecasts that keep planes and ships safe and prepare countries for a potential hurricane landfall.

Now, meteorologists are about to lose access to three of those satellites.

On June 25, 2025, the Trump administration issued that the Defense Meteorological Satellite Program, DMSP, and the Navy's Fleet Numerical Meteorology and Oceanography Center would terminate data collection, processing and distribution of all DMSP data no later than June 30. The until July 31 following a request from the head of NASA's Earth Science Division.

I am who studies lightning in hurricanes and helps train other meteorologists to monitor and forecast tropical cyclones. Here is how meteorologists use the DMSP data and why they are concerned about it going dark.

Looking inside the clouds

At its most basic, a weather satellite is a high-resolution digital camera in space that takes pictures of clouds in the atmosphere.

These are the satellite images you see on most TV weather broadcasts. They let meteorologists see the location and some details of a hurricane's structure, but only during daylight hours.

Meteorologists can use infrared satellite data, similar to a thermal imaging camera, at all hours of the day to find the coldest cloud-top temperatures, highlighting areas where the highest wind speeds and rainfall rates are found.

But while visible and infrared satellite imagery are valuable tools for hurricane forecasters, they provide only a basic picture of the storm. It's like a doctor diagnosing a patient after a visual exam and checking their temperature.

For more accurate diagnoses, meteorologists rely on the DMSP satellites.

The three satellites orbit Earth 14 times per day with instruments, or SSMIS. These let meteorologists look inside the clouds, similar to how an MRI in a hospital looks inside a human body. With these instruments, meteorologists can pinpoint the storm's low-pressure center and identify signs of intensification.

Precisely locating the center of a hurricane improves forecasts of the storm's future track. This lets meteorologists produce more accurate hurricane watches, warnings and evacuations.

Hurricane track forecasts have since 1990. However, forecasting , so the ability of DMPS data to identify signs of intensification is important.

About 80% of major hurricanes—those with wind speeds of at least 111 mph (179 kilometers per hour)— at some point, ramping up the risks they pose to people and property on land. Finding out when storms are about to undergo intensification allows meteorologists to warn the public about these dangerous hurricanes.

Where are the defense satellites going?

NOAA's Office of Satellite and Product Operations described the reason for turning off the flow of data as a need to mitigate "."

The three satellites have already operated for longer than planned.

The DMSP satellites were launched between 1999 and 2009 and were . They have now been operating for more than 15 years. The United States Space Force recently concluded that the DMSP satellites would reach the , so the data would likely have gone dark soon.

Are there replacements for the DMSP satellites?

Three other satellites in orbit—NOAA-20, NOAA-21 and Suomi NPP—have a microwave instrument known as the .

The advanced technology microwave sounder, or ATMS, can provide data similar to the special sensor microwave imager/sounder, or SSMIS, but . It provides a more washed-out view that is less useful than the SSMIS for pinpointing a storm's location or estimating its intensity.

The U.S. Space Force began using data from a , ML-1A, in late April 2025.

ML-1A is a microwave satellite that will help replace some of the DMSP satellites' capabilities. However, the government hasn't announced whether the ML-1A data will be available to forecasters, including those at the National Hurricane Center.

Why are satellite replacements last minute?

Satellite programs are planned over many years, even decades, and are very expensive. The launched its first satellite in 2016 with plans to operate until 2038. Development of the planned successor for GOES-R .

Similarly, have been underway since the early 2000s.

Delays in developing the satellite instruments and funding cuts caused the National Polar-orbiting Operational Environmental Satellite System and Defense Weather Satellite System to be canceled in 2010 and 2012 before any of their satellites could be launched.

The includes an increase in funding for the next-generation geostationary satellite program, so it can be restructured to reuse spare parts from existing geostationary satellites. The budget also terminates contracts for ocean color, atmospheric composition and advanced lightning mapper instruments.

A busy season remains

The 2025 Atlantic hurricane season, which runs from June 1 to Nov. 30, is , with . The runs from the middle of August to the middle of October, after the DMSP satellite data is set to be turned off.

Hurricane forecasters will continue to use all available tools, including satellite, radar, weather balloon and dropsonde data, to monitor the tropics and issue hurricane forecasts. But the loss of satellite data, along with , could .

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