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.
- Timezones in the US change twice a year, in the fall and spring, with an offset of 1 hour in either direction.
- 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.
- 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.
- 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.
- 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.
- These switches happen at 2:00am, so the clock becomes 1:00am in the fall or 3:00am in the spring.
- 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.
- 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.
- 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.