Mountain time, explained
MDT. Mountain Daylight Time.
Mountain time is MDT right now — Mountain Daylight Time, UTC−6. It is 12:48 AM in Denver.
Where you are
—
Your own clock, worked out when the page opens.
Sunrise
7:10 AM
11 h 12 min of daylight.
Sunset
6:22 PM
Golden hour from 5:46 PM.
The next change
1 Nov
MDT to MST: the clocks go back an hour. Sunset moves from 5:59 PM to 4:58 PM.
MST and MDT are two clocks, an hour apart.
“Mountain time” is a place's clock, not a fixed offset. From the second Sunday in March to the first Sunday in November it is Mountain Daylight Time, UTC−6; the rest of the year it is Mountain Standard Time, UTC−7. Writing MST in July, or reading an MST meeting as an MDT one, moves it by an hour — which is why this page never writes one for the other, and why every Sol page names the zone as the tables have it for the instant in question.
The zone id is America/Denver, with America/Boise for the south of Idaho. Mountain time covers Colorado, Utah, New Mexico, Wyoming and Montana, most of Idaho, and parts of Oregon, Nevada, Texas, Kansas, Nebraska and the Dakotas; Alberta keeps the same clock under America/Edmonton. Arizona does not, except the Navajo Nation: America/Phoenix keeps MST, UTC−7, all year with no change at all.
The changes in 2026.
The light in Denver now.
You stand at the middle of Denver’s horizon. The dots are the sun’s path today. Walk the hours, or drag the sky to turn it.
How it knows.
The browser’s own tables
Every time here is read from the zone tables your browser carries, the IANA database by its zone id (America/Los_Angeles, not “Pacific”), never from an offset typed by hand. A zone’s name is what the tables say for the moment asked: PDT in a Pacific summer, PST in its winter.
Hours the clocks change
A clock change removes an hour in spring and repeats one in autumn. Both are reported rather than moved: an hour that does not exist is named, with the time the clock reads instead, and an hour that happens twice is given both ways.
The light beside the clock
An hour alone says nothing about the sky, so each clock stands beside its day’s light, worked out for the city from the sun’s position. The pages are rebuilt every night, and every time is worked out again in your browser when the page opens.
Convert it, or read another clock.
Pacific time, explainedPST or PDT, and when Central time, explainedCST or CDT, and when Eastern time, explainedEST or EDT, and when UK time, explainedGMT or BST, and whenEvery place, its own light.
Sol for iPhone is coming soon, with your places side by side under their own skies, each on its own clock. Leave your address for one email when it ships.
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