When record temperatures wracked the UK in late July, Google Cloud’s data centers in London went offline for a day, due to cooling failures. The impact wasn’t limited to those near the center: That particular location services customers in the US and Pacific region, with outages limiting their access to key Google services for hours. Oracle’s cloud-based data center in the capital was also struck down by the heat, causing outages for US customers. Oracle blamed “unseasonal temperatures” for the blackout.

The UK Met Office, which monitors the weather, suggests that the record heat was an augur of things to come, which means data centers need to prepare for a new normal.

The World Meteorological Organization (WMO) says there’s a 93 percent chance that one year between now and 2026 will be the hottest on record. Nor will that be a one-off. “For as long as we continue to emit greenhouse gases, temperatures will continue to rise,” says Petteri Taalas, WMO secretary general. “And alongside that, our oceans will continue to become warmer and more acidic, sea ice and glaciers will continue to melt, sea level will continue to rise, and our weather will become more extreme.”

That weather shift will have an impact on all human-made infrastructure—including the data centers that keep our planet’s collective knowledge online.

The question is whether they are prepared. “From my point of view, there is an issue with existing data center stock that’s been built in the UK and Europe,” says Simon Harris, head of critical infrastructure at data center consultancy Business Critical Solutions. But it doesn’t stop there. Forty-five percent of US data centers have experienced an extreme weather event that threatened their ability to operate, according to a survey by the Uptime Institute, a digital services standards agency.

Data center cooling systems are built using a complicated, multi-stage process, says Sophia Flucker, director at UK data center consulting firm Operational Intelligence. This may include analyzing temperature data from a weather station close to the point where the data center will be built.

The problem? That data is historical and represents a time when temperatures in the UK didn’t hit 40 degrees Celsius. “We’re on the fringes of a changing climate,” says Harris.

“It wasn’t that long ago that we were designing cooling systems for a peak outdoor temperature of 32 degrees,” says Jon Healy, of the UK data center consultancy Keysource. “They’re over 8 degrees higher than they were ever designed for.” The design conditions are being increasingly elevated—but data center companies, and the clients they’re working for, operate as profit-driven enterprises. Data from consultancy Turner & Townsend suggests that the cost of building data centers has risen in almost every market in recent years, and construction companies are advised to keep costs down.

“If we went from 32 degrees to 42 degrees, blimey,” says Healy. “You’re having to make everything significantly larger to support that very small percentage of the year” when temperatures rise. “It’s got to be done with caution.”