A severe windstorm that battered Colorado last week has unexpectedly impacted the United States’ most precise timekeeping infrastructure, causing the national time standard to fall behind by 4.8 microseconds. The incident occurred when powerful winds knocked out power to the National Institute of Standards and Technology’s (NIST) Boulder campus, disrupting the operation of atomic clocks that maintain official US time.
The disruption began on December 17, 2025, when utility power failed at NIST’s Colorado facility during the intense windstorm. Although backup generators were available, a subsequent failure in one of these critical backup systems caused approximately 16 atomic clocks to lose connection with NIST’s measurement and distribution systems. These clocks, including hydrogen masers and cesium beam instruments, normally maintain the nation’s time standard through a weighted average of their readings.
According to NIST supervisory physicist Jeffrey Sherman, the lapse resulted in NIST’s Coordinated Universal Time (UTC) becoming 4.8 microseconds slower than the correct standard. To contextualize this deviation, NIST spokesperson Rebecca Jacobson noted that a human blink typically takes approximately 350,000 microseconds (0.35 seconds).
While the time discrepancy would be imperceptible to the general public, experts warn that such deviations could have more serious implications for critical infrastructure systems. The official US time standard serves as a reference for telecommunications networks, GPS signals, financial transactions, and other time-sensitive applications where precision is paramount.
As of December 22, utility power had been restored to NIST’s Boulder facilities, and assessment and repair activities are currently underway. The incident highlights the vulnerability of even the most sophisticated scientific infrastructure to extreme weather events and the importance of robust backup systems for maintaining critical national standards.