Daylight saving time changes in Colorado, United States

Colorado uses the IANA time zone identifier America/Denver. The current local offset is UTC-6 / MDT.

Best Time to Call Colorado

Business hours in Colorado (9 AM-5 PM local time) fall at these local times elsewhere:

• Sao Paulo: 12:00 PM - 8:00 PM ( Partial overlap)
• Frankfurt: 5:00 PM - 1:00 AM (next day) ( Partial overlap)
• Johannesburg: 5:00 PM - 1:00 AM (next day) ( Partial overlap)
• Singapore: 11:00 PM - 7:00 AM (next day) ( Outside normal hours)
• Hong Kong: 11:00 PM - 7:00 AM (next day) ( Outside normal hours)
• Istanbul: 6:00 PM - 2:00 AM (next day) ( Partial overlap)
• Auckland: 4:00 AM (next day) - 12:00 PM (next day) ( Outside normal hours)

Times shown reflect current UTC offsets and may shift by up to an hour around daylight saving transitions.

Current Time in Cities of Colorado, United States

About Time in Colorado

The Station That Sets North America's Clocks

Just outside Fort Collins, Colorado sits a radio transmitter most Americans have never heard of, even though tens of millions of their clocks, watches, and appliances rely on it every day. The station, known by its call sign WWVB, is operated by the National Institute of Standards and Technology and broadcasts a continuous time signal on a 60 kilohertz carrier wave that most radio controlled clocks across the United States, Canada, and Mexico use to keep themselves accurate. The signal traces back to a much smaller experiment: in July 1956, engineers in nearby Boulder began broadcasting from a station called KK2XEI at just 1.4 watts of power, so weak that its main purpose was simply to prove the radio path itself was stable enough to carry a reliable frequency. That signal was strong enough to be detected as far away as Harvard University in Massachusetts.

By 1963, the operation had grown into WWVB proper, relocated to Fort Collins in part because the site's highly alkaline soil gave it exceptional ground conductivity for broadcasting, while still being close enough to Boulder, about fifty miles away, to staff easily. The station's time signal is synchronized to an ensemble of atomic clocks maintained in Boulder and calibrated against NIST's cesium fountain standard, the primary civilian time reference for the United States. What began as a tool for calibrating satellite and missile guidance systems eventually became something far more everyday: the quiet signal that keeps household alarm clocks, wall clocks, and wristwatches in sync with official time, without their owners ever realizing where that accuracy comes from.

A Law Waiting on Washington

Colorado has already decided, at least on paper, that it wants to stop changing its clocks twice a year, but state law alone cannot make that happen. In 2022, the Colorado legislature passed House Bill 22-1297 by a wide bipartisan margin, and Governor Jared Polis signed it into law, formally committing the state to year round daylight saving time. The bill was sponsored by state Senator Jeff Bridges, who argued that the biannual time change carried real costs in the form of increased heart attacks, more traffic accidents, and reduced workplace productivity in the days surrounding each shift.

The catch is built into federal law itself. Under the existing Uniform Time Act, individual states are permitted to opt out of daylight saving time entirely and remain on standard time year round, which is the choice Arizona and Hawaii have made, but no state is currently allowed to adopt daylight saving time permanently on its own. Colorado's law is therefore written to take effect only once Congress authorizes states to make that switch, something proposals like the Sunshine Protection Act have repeatedly attempted and failed to accomplish. As a result, Coloradans have continued to change their clocks each spring and fall since 2022 exactly as they did before the bill passed, with a state law on the books that cannot yet be enforced, waiting on a federal decision that has not arrived.

Denver's Venetian Clock Tower

Rising above downtown Denver is a slender brick and terracotta tower that has told the city's time since 1911, long after the department store it was built to advertise disappeared entirely. The Daniels and Fisher Tower was commissioned by William Cooke Daniels, who had traveled to Venice and returned determined to bring a piece of it home, modeling the structure directly on the Campanile of St. Mark's in the Piazza San Marco. At roughly 325 feet, it was the tallest building between the Mississippi River and the state of California at the time of its completion, a striking claim for a city that was still a relatively young frontier capital.

The tower carries a Seth Thomas clock with faces on all four sides, its hour hands measuring eight feet long and its minute hands six feet, along with a bronze bell weighing more than two tons housed near the top. When the Daniels and Fisher department store closed and was absorbed by the May Company in 1958, the surrounding store building was eventually demolished during Denver's Skyline Urban Renewal Project of the early 1970s, but a group of local preservationists successfully fought to save the clock tower itself, and it was added to the National Register of Historic Places in 1969. Today the tower still keeps time over the city's skyline, having outlived the very business it was built to promote by more than half a century.

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