When does Daylight Saving Time start and end in the US?

Under US federal law (Energy Policy Act of 2005), Daylight Saving Time begins at 2:00 AM on the second Sunday in March (clocks jump forward 1 hour) and ends at 2:00 AM on the first Sunday in November (clocks fall back 1 hour).

Does the time difference between Denver and New York change during DST?

No. Because both Denver (Mountain Time) and New York (Eastern Time) change their clocks simultaneously on the exact same Sunday morning at 2:00 AM local time, the time difference between them remains exactly 2 hours all year round.

Why is Arizona different during Daylight Saving Time?

Arizona does not observe Daylight Saving Time. When Eastern Time springs forward to EDT in March, Arizona stays on Mountain Standard Time (UTC-7). This widens the gap between Arizona and New York from 2 hours to 3 hours from March through November.

Daylight Saving Time (DST) Intelligence

MST to EST During Daylight Saving Time: Schedule & Rules

Understand how "Spring Forward" and "Fall Back" affect Mountain and Eastern Time. Transition dates, abbreviation shifts (MST → MDT, EST → EDT), and the Arizona gap.

The Golden Rule

Denver and New York are ALWAYS 2 hours apart.

Because both Colorado and New York follow standard US Daylight Saving rules, both switch on the exact same date and time. In winter it is MST to EST (2 hours). In summer it is MDT to EDT (2 hours). The only exception is Arizona.

Important Exception

Arizona shifts to 3 hours gap →

Read our full Arizona time guide

Official US DST Transition Dates (2024 – 2027)

Select a year to see exact spring-forward and fall-back clock shift dates:

Spring Forward (2026)

March 8, 2026

At 2:00 AM local time, clocks jump forward to 3:00 AM. You lose 1 hour of sleep.

• Mountain: MST (UTC-7) → MDT (UTC-6)
• Eastern: EST (UTC-5) → EDT (UTC-4)

Fall Back (2026)

November 1, 2026

At 2:00 AM local time, clocks repeat 1:00 AM. You gain 1 extra hour of sleep.

• Mountain: MDT (UTC-6) → MST (UTC-7)
• Eastern: EDT (UTC-4) → EST (UTC-5)

The 1-Hour Shift Window on Transition Sunday

Have you ever wondered what happens during the exact hours clocks change? Because the United States shifts clocks at 2:00 AM local time rather than a single unified moment, there is a temporary anomaly:

Spring Forward Sunday: At 2:00 AM Eastern Time, New York jumps forward to 3:00 AM EDT. However, Denver is still at 12:00 midnight MST! For exactly two hours (until 2:00 AM Mountain Time arrives), the difference between Denver and New York is briefly 3 hours.
Fall Back Sunday: At 2:00 AM Eastern Time, New York falls back to 1:00 AM EST. But Denver has not fallen back yet. For two hours, the gap is temporarily 1 hour until Denver hits 2:00 AM and falls back as well.

Why our converter is superior: MSTtoEST.com uses true IANA standard timezone timestamps. If you pick March 8 at 2:15 AM, our algorithms calculate the exact real-time offset down to the minute.

Frequently Asked Questions About MST & EST Daylight Saving Time

What does MDT and EDT mean?

MDT stands for Mountain Daylight Time (UTC-6) and EDT stands for Eastern Daylight Time (UTC-4). These are the active daylight saving time designations between March and November.

Will the US ever make Daylight Saving Time permanent?

The Sunshine Protection Act has been proposed in the US Congress multiple times to make Daylight Saving Time permanent nationwide. However, as of 2026, the bill has not passed into law, and the standard semi-annual clock changes remain in effect.