As extreme heat stifles communities around the world this week, the World Meteorological Organization (WMO) said that it has “no immediate plans” to give heatwaves names. The July 19th announcement seems to pump the brakes on growing calls to come up with a strategy for ranking and naming heatwaves around the world.

In the US, heat kills more people than any other weather-related disaster. Globally, it kills 5 million people a year. But heat spells haven’t always spurred the same careful preparations people might take to, say, shelter from a major storm. The goal of naming heatwaves would be to make it easier to communicate the risks they pose to the public so that people can take measures to stay safe.

For decades, names have played a big role in early warnings for dangerous storms. Warning people about hurricane “Sandy” or “Harvey” just became a lot easier than identifying a storm by latitude and longitude. The US’s National Hurricane Center started giving Atlantic storms monikers from an official list in 1953. Currently, the WMO maintains rotating lists of names for the Atlantic and other regions.

Some advocates want to apply a similar naming mechanism to heatwaves. Seville, Spain, is set to become the first city in the world to test out the idea later this year. Officials in Athens, Greece, and California have contemplated doing the same. But the WMO apparently has some reservations, saying that it’s “currently considering the advantages and disadvantages of naming heatwaves.”

“What has been established for tropical cyclone events may not necessarily translate easily across to heatwaves,” the WMO said in its news release this week. “Caution should be exercised when comparing or applying lessons or protocols from one hazard type to another, due to the important differences in the physical nature and impacts of storms and heatwaves.”

“False alarms” are one concern for the WMO. Heatwaves can be forecast up to 10 days out in many parts of the world. But if the forecast for an extreme heatwave is inaccurate — maybe it’s not as hot as expected or it hits a different region than anticipated — then people might lose faith in the warnings and stop heeding them.

The other caveat with heat, the WMO says, is that heat-related deaths can happen even when it’s not extraordinarily hot outside. If someone is continuously exposed to more sweltering conditions, say, in the workplace or in a home without air conditioning, they can become ill even if there isn’t an officially declared heatwave.

To prevent confusion ahead of a potential disaster, the WMO also says that any “pilot heatwave naming” should at least be tied into a country’s official warning system in the absence of a broader international framework.

Seville is piloting a project this year that will test a new alert system to warn residents ahead of a heatwave. Extreme heat events will be categorized based on their severity, and those forecast to have the greatest impact on the city will get a name. The first five have already been chosen: Zoe, Yago, Xenia, Wenceslao, and Vega.

“We are the first city in the world to take a step that will help us plan and take measures when this type of meteorological event happens—particularly because heat waves always hit the most vulnerable,” Antonio Muñoz, the mayor of Seville, said in a June 21st press release.

Parts of Europe literally buckled and burned under a brutal heatwave this week — even in places with typically milder summers. In the UK, record-breaking temperatures buckled train tracks and even an airport runway. London’s fire service responded to more blazes in a day than it had since World War II, according to Sadiq Khan, the city’s mayor. And 100 million people in the US are under heat alerts today.

Heatwaves are becoming more frequent and more intense as greenhouse gas emissions heat our planet. More than a third of heat deaths can be attributed to climate change, according to research published last year.