The International Telecommunication Union and the World Meteorological Organization warned governments and regulators on Monday to protect the radio frequency spectrum that weather forecasts, early warning systems and climate monitoring depend on.

The two United Nations agencies issued the warning alongside a joint handbook carrying updated guidance on the use and defence of frequencies reserved for meteorological systems. Those systems observe the atmosphere, oceans and land, and transmit the data that supports life-saving early warnings, reliable forecasting and long-term climate monitoring.

The timing is not accidental. The handbook reflects concern inside both organisations that industry and government sectors are racing to acquire as much spectrum as possible for wireless communications, satellite services and their own environmental data needs. Every megahertz handed to a mobile operator or a commercial satellite constellation is a megahertz that meteorologists cannot easily replace.

Why does interference matter for forecasts?

The ITU and WMO stated plainly that radio frequency interference degrades the accuracy and availability of data needed for early warning systems, weather forecasting and climate monitoring. Degraded data, in turn, weakens the ability of governments and communities to prepare for and respond to environmental hazards.

The physics makes the problem acute. Some satellite sensors measure very weak, naturally occurring signals at specific frequencies, which makes protection from harmful interference particularly important. Weather radar, lightning location systems, aircraft and marine observations, hydrological monitoring systems and other platforms also rely on these bands to collect and exchange data.

There is no engineering workaround. The atmosphere dictates which frequencies work. The agencies made that point without ambiguity.

What does this change for regulators?

ITU secretary-general Doreen Bogdan-Martin framed the issue in the bluntest terms. "Preventing harmful radio interference is a matter of public safety and can save lives," she said in a joint statement. "Interference-free spectrum keeps weather forecasts accurate, emergency alerts and warnings timely, and climate data reliable – so communities can prepare, respond and build resilience."

Her WMO counterpart, secretary-general Celeste Saulo, stressed the physical constraints that regulators cannot legislate away.

"The radio-frequency spectrum is a finite natural resource. Meteorology relies on specific bands, determined not by choice, but by the physical properties of the atmosphere itself," Saulo said. "They enable observations that no other frequencies can provide. These bands must be protected."

For national regulators, the message lands at a difficult moment. Mobile operators seeking mid-band spectrum for 5G and, increasingly, 6G research have pressed for access to frequencies adjacent to, and in some cases overlapping, passive Earth observation bands. The ITU and WMO did not name specific industries or auctions, but the handbook's underlying concern is clear: commercial demand for spectrum is growing faster than the willingness of buyers to respect the boundaries of scientific use.

The handbook and the seminar

The agencies formally released the handbook on Monday, the first day of the Global ITU-WMO Seminar on Spectrum Use for Meteorology. Experts at the seminar plan to review recent and upcoming international spectrum decisions relevant to meteorological and Earth observation services, including outcomes of the latest ITU World Radiocommunication Conferences.

That review matters. World Radiocommunication Conferences set the international treaty-level allocations that national regulators generally follow, and the outcomes of the most recent conference are still working their way into national policy. The seminar gives meteorologists a forum to argue for protection before the next round of allocation decisions locks in.

The handbook itself serves as the practical instrument. It consolidates updated guidance on which frequencies meteorological systems use, how interference harms them, and what governments and regulators should do to keep the bands viable. The two agencies intend it as a reference for the officials who will decide, band by band, whether commercial appetite or scientific necessity prevails.

The stakes extend beyond weather apps. Hydrological monitoring supports water management. Aircraft and marine observations feed aviation and maritime safety. Long-term climate records depend on uninterrupted, consistent measurements at the same frequencies over decades.

The next test will come as governments weigh future spectrum awards against the guidance now on paper. The ITU and WMO have set out their position; the allocation decisions remain with national regulators and the next World Radiocommunication Conference cycle.