The United States briefly slipped behind the rest of the world in timekeeping after a powerful storm struck Colorado last week, disrupting operations at the country’s official timekeeping facility. Following the incident, American time was recorded as lagging by 4.8 microseconds compared to the global standard, a tiny difference that nevertheless raised serious concerns about the resilience of critical infrastructure systems.
The disruption occurred at the National Institute of Standards and Technology (NIST) facility in Boulder, which houses more than a dozen atomic clocks responsible for determining the nation’s official time. Hurricane-force winds swept across Colorado, damaging trees and electrical infrastructure and prompting the state’s largest power provider to carry out precautionary shutdowns to reduce fire risks. While the atomic clocks themselves continued to operate using battery backup systems, a failure in a backup generator caused a brief interruption in measurement and distribution systems.
As a result, Coordinated Universal Time as maintained by NIST, known as UTC(NIST), slowed by 4.8 microseconds. UTC(NIST) is the reference used to determine official time across the United States and differs slightly from the global UTC used internationally. The issue did not stop the clocks from ticking, but it interrupted how their signals were measured and distributed, leading to the temporary time discrepancy.
According to NIST supervisory research physicist Jeff Sherman, the time gap was both significant and minimal at the same time. While a few microseconds may seem negligible to the average person, such deviations can have real-world consequences. Precise time synchronization is essential for telecommunications networks, financial transactions, power grids, GPS navigation systems and internet services. Even the smallest error can ripple across interconnected systems that rely on exact timing to function properly.
Sherman explained that during the outage, the connection between some atomic clocks and NIST’s measurement systems failed, meaning that Boulder-based Internet Time Services no longer had an accurate reference point. Although no major disruptions were reported, the incident highlighted how vulnerable highly precise systems can be during extreme weather events.
NIST has served as America’s official timekeeper since 2007. At its Boulder laboratory, 20 atomic clocks operate on a rotating basis, with roughly 10 to 15 active at any given moment. These include hydrogen masers and caesium beam clocks, which are constantly monitored by primary and alternate multi-channel measurement systems. Data from these clocks is fed into advanced computer algorithms that calculate the exact national time and align it with international standards.
Power has since been fully restored at the NIST facility, and technicians are conducting assessments and repairs to ensure system stability. The incident has sparked renewed discussion about safeguarding critical scientific infrastructure as climate-driven extreme weather events become more frequent, reminding experts that even the most advanced systems are not immune to natural forces.
