I'm traveling this week. Apple invited me to participate in the International Apple Distinguished Educators Institute in Cork, Ireland. My wife and I added a few days before and after the Institute to explore Dublin and Cork.
Soon after we arrived, I checked my calendar. I'd added a number of reminders concerning our travel schedule and noticed those appointments were off by five hours. Five hours is the difference between my east coast U.S. time zone and the one here in Ireland. This was easily fixed. Here's how.
Enable Time Zone Support. Go to Settings >Mail, Contacts, Calendars. Scroll down to Time Zone Support. Turn it on. When I did this, all of my calendar entries magically adopted my new time zone.
Turn off Time Zone Support when you're not using it. If it's on and set for a different time zone from the one you're in, your calendar events may appear at the wrong times.