This week's heatwave is not a background condition - for data centres and the businesses that depend on them, it is an active operational risk.

A red heat-health alert is in force across six English regions (from 1am Wednesday 24 June to 11pm Thursday 25 June 2026), with UKHSA warning of impacts reaching transport, energy supplies and businesses, not just public health. The Met Office reports a significant heatwave across Europe, with Spain, France and Italy forecast into the high 30s, some locations exceeding 40°C, and temperatures around 10°C above mid-June averages.

'Cloud' has a postcode. Data centres are the infrastructure hubs of the digital economy, and extreme heat is not a metaphorical stress test. Cooling performance, equipment tolerances, staff safety and the knock-on effects of any degraded service all tighten simultaneously.

A sector contributing to its own stress test

This is where it can become uncomfortable. The infrastructure under stress from this week's heat is itself a material contributor to the emissions that drive warming. The IEA estimated global data centre electricity consumption at around 415 TWh in 2024 (approximately 1.5% of all global electricity use) projected to more than double by 2030 as AI demand accelerates. The sector has no shortage of net zero commitments. The gap between those commitments and demonstrable delivery is, in some cases, widening. There is a genuine circularity here: the heatwave stresses the data centre; the data centre, at aggregate scale, contributes to the conditions that produce the heatwave. That loop will not close through marketing language.

Designated Critical National Infrastructure: The policy stakes

The UK government has already moved the sector into a different category. On 12 September 2024, data centres were designated Critical National Infrastructure, their continuity now a matter of national resilience, not just commercial performance. The dependency is real: 28% of UK businesses and 62% of large businesses rely on data centre services. The blast radius of a failure is economic before it is technical.

Heat failure is not hypothetical. Government factsheets cite July 2022, when two data centres serving an NHS trust failed during a heatwave, disrupting clinical IT across multiple hospitals and generating £1.4m in unplanned recovery costs.

A hardening regulatory framework

The legal and regulatory framework is hardening accordingly. The proposed Cyber Security and Resilience (NIS) Bill, introduced in November 2025, would bring data centres within the UK's essential-services cyber resilience regime. The proposal contemplates Ofcom acting as regulator and introduces more formalised incident-reporting obligations, including rapid initial notification requirements and follow-up reporting duties. While the precise obligations remain subject to the legislative process, the direction of travel is clear: greater scrutiny, greater accountability and higher expectations of demonstrable resilience.

Our view

The UK has taken the right structural steps, as CNI designation and the NIS Bill represent a serious policy commitment. The next step is translating that commitment into a framework that operators, customers and regulators can all interrogate with confidence.

That means standardised resilience testing, transparent reporting requirements and an implementation timeline for the NIS regime that keeps pace with the real-world risks the sector is already facing.

Five questions every operator should be able to answer

The documents that matter most in a heatwave are the ones that answer five questions:

• Who declares a major incident, and who controls external communications?
• What constitutes a reportable incident, and how is the point of first awareness evidenced?
• What information must be available immediately, and what can follow later?
• How and when are customers notified, by whom, and in what terms?
• What evidence of preparedness is actually promised?

The next decade's disputes will not be about whether organisations had sustainability ambitions or resilience policies. They will be about whether those ambitions were evidenced, tested and governed. In a major heatwave, the distinction between a commitment and a capability becomes impossible to hide.