Twice a year, many people in IT often get mixed up by time zones in the US. Understandably, as it is a little tricky to wrap your head around. Here are some tips when sorting it all out in the US.

1. Timezones in the US change twice a year, in the fall and spring, with an offset of 1 hour in either direction.
2. The exception to #1 are the States of Arizona (most of it) and Hawai’i – they never change their clocks like the rest of the US.
3. In the spring, around March, the US switches to Daylight Savings Time, so we set our clocks forward 1 hour, giving us more light in the early evening.
4. In the fall, around November, the US switches to Daylight Standard Time, so we set our clocks back 1 hour, giving us more light in the early morning.
5. Part of the confusion is Daylight Savings Time and Daylight Standard Time both have the initials of DST. When abbreviating, it’s better to include your time zone. As an example: EDT is Eastern Daylight Time which starts in the spring, and EST is Eastern Standard Time which starts in the fall.
6. These switches happen at 2:00am, so the clock becomes 1:00am in the fall or 3:00am in the spring.
7. Be careful of #6 above. The swing appears to be two hours, but it’s not. Since time is relative, the switch is only 1 hour in either direction.
8. Since the time switch is done by timezones, in the single hour that the East Coast sets is clocks backward in the fall by 1 hour, and Midwest hasn’t begun the change, clocks in New York will be set to the same time as Chicago; typically an hour apart. This hour-long cascade happens in each timezone as the local time changes around the US.
9. Most other countries, but not all, also shift their clocks, but not on the same dates as the US. This causes some crazy scheduling twice a year with people in different countries than the US.

If you want to get a bigger picture of all this, you can consult NIST which is the US standard for keeping time.