A storm knocked US time off by 4.8 microseconds: How a windstorm briefly messed with America’s clock

Time is that one constant we all share across the world; it's the same everywhere on Earth, ticking forward at the exact same pace no matter where you stand. No matter if you're sipping coffee in New Delhi at 9 AM or watching the sunset in Florida at the same universal moment, that underlying second-by-second flow doesn't change or speed up for anyone. What changes is how we slice it up into time zones to match our daily lives with the sun's rhythm.

But do you know that time lagged by some microseconds in America, and all this happened because of a windstorm!

US time lagged by 4.8 microseconds

Storm impacts US time

A windstorm battered Colorado last week, knocking out power at the National Institute of Standards and Technology (NIST) in Boulder and throwing the US official time standard off by 4.8 microseconds. Hurricane-force winds toppled trees and strained the grid, forcing Xcel Energy to shut down power in high-fire-risk areas for safety.

NIST's atomic clocks keep ticking on battery backups, but a backup generator failed, disturbing connections and measurement systems and causing the drift in UTC (NIST).

Although this tiny glitch took less time than a blink, it shows how fragile our hyper-precise timekeeping is amid extreme weather. Power is back on now, with repairs underway to realign US time to global standards.

Atomic clocks keep ticking

NIST has over a dozen ultra-precise atomic clocks in Boulder, including cesium beams and hydrogen masers, that measure time through atomic vibrations. During the blackout, all clocks ran flawlessly on batteries, as physicist Jeff Sherman confirmed to NPR. The snag hit when a backup generator conked out, breaking links to measurement gear and internet time services. This "atomic ensemble" normally averages 10–15 clocks for UTC (NIST), the US standard since 2007.

The 4.8-microsecond lag

US time slipped 4.8 microseconds behind global UTC, about 1/350,000th of a blink, due to the outage. GPS signals could wobble, telecom networks glitch, and power grids falter without exact sync. NIST alerted high-end users to alternate sources. The anomaly arose from disconnected clocks, not clock failure. By Sunday, teams realigned systems post power restoration.

Why time precision is important

Even a matter of microseconds packs a punch in modern life. Stock trades execute in nanoseconds; GPS needs sub-microsecond accuracy for navigation. Telecom syncs calls and data, and catering to them all, delayed signals mean dropped connections. Infrastructure like smart grids depends on it too, and desyncs like this might cascade into blackouts.